He showed up late for his own 49th birthday celebration Sunday night. Then, on Monday morning, he announced he was backing George Bush for vice president at the exact moment his fellow Virginia delegates were voting 3 to 2 to support Jack Kemp.

Today he arrived 50 minutes late for a pep rally with the California delegation after getting lost in the cavernous, mazelike lobby of the Detroit Plaza Hotel, and had to settle for the last seat at the back end of the rostrum.

For Virginia Gov. John N. Dalton, the Republican National Convention sometimes has seemed more like a series of comic mixups than a chance to meet and mingle with his fellow party members. That has not stopped the conservative Republican from having a good time, or from enjoying the trappings and perquisites of what some critics have called "the imperial governorship."

While most Virginians arrived here by commercial flight, Dalton and his wife Eddy came to town Sunday in a private Lear jet owned by millionaire industrial Bruce Gottwald, whose family donated $18,000 to Dalton's 1977 gubernatorial campaign.

While most of the delegates rely on shuttle buses to get from their hotel to the convention arena and back again, Dalton is chauffeured in a camper van, accompanied by Gottwald and one of a squad of three Virginia state troopers dispatched here to provide round-the-clock bodyguard service.

While other delegates spend most of the daylight hours shopping or basking at poolisde at the hotel, Dalton shuttles from meeting to meeting downtown, talking up Ronald Reagan and Republicanism to delegates from other states many of whom have never heard of John Dalton.

The bodyguards, the chauffeur, the pep rallies -- all are symbols of Dalton's status as the state's hightest office-holder. At the same time, they tend to separate him from his fellow Virginia delagates, some of whom complain privately that he is aloof and out of touch with them.

Few will criticize Dalton in public. Arlington delegate Jade West, an avid Reaganite, complains about "that abominable gas tax" that Dalton supported and that passed the Virginia General Assembly earlier this year. But she also stresses that, "I agree with him on most issues."

Another arch conservative, Del. Lawrence Pratt of Fairfax, says "I think I'm still on his list," because Pratt refused to back the gasoline sales tax increase. But that's all Pratt will say about it.

The strains are there. They actualy began four years ago when most of the Virginia delegates supported Ronald Reagan and John Dalton, then a lieutenant governor, backed Gerald Ford.

"There were some right hard feeling four years ago," Dalton concedes, adding quickly, "but I don't see anything like that this time.There's no aloofness or animosity -- everybody is really together."

Still, some Reagnites were upset when Dalton waited until the end of March to back their man this year. Before succumbing to what he considered the inevitable, he had flirted privately with George Bush's candidacy and publicly with Gerald Ford's.

There was some early talk of denying Dalton a place on the delegation, but Reagan campaign leaders quashed that move in the name of party unity. Dalton was even voted chairman of the state delegation, although Reagan state campaign chairman John Alderson really calls the shots for most of the delegates, and Warrenton lawyer Guy O. Farley has emerged as their natural leader.

It was Farley who forced the vice presidential poll yesterday that Dalton and other party leaders had hoped to avoid. When the results were in, Kemp had 31 votes to just 10 for Dalton's choice, George Bush.

One man who received no voters in the poll was Dalton himself, who last spring had dropped hints that he would be pleased and honored to accept the vice presidential nod. Friends say he secretly was hoping Regan would pick him, but the dream quickly faded when became clear that the Reagan people saw no advantage in having a conservative former governor with no foreign policy experience balance his ticket with a conservative governor with a similar gap in his resume.

Some of the gap between Dalton and his delegates appears to be personal. Despite his success as a politician, friends say Dalton is an extremely, private man, almost an introvert, who sometimes finds small talk painful.

"I remember four years ago John was sitting on a couch by himself,"," says one friend. "He's just very quiet and some people mistake that for not being friendly."

Dalton himself dismisses any notion that he is out of touch with other Virginians. Of the Kemp drive, he says: "I've got some real close friends involved in that. I wasn't surprised about how much support he has and I'm not trying to tell anybody how they should vote."

Although he is far out of contention. Dalton still enjoys basking in the spotlight, even if he only catches a few small rays. He shared both a podium and a crowded elevator with George Bush, William Simon and Alexander Haig this morning, then gushed about how great it was "to meet and talk to people you usually just read about."

Bush, whom many expect to get the vice presidential nod, dominated most of the question-and-answer session at which he and the others appeared. Dalton got a chance to chime in at one session when a delegate asked about how Reagan would deal with strikes by public employe unions.

"In my state we don't have any strikes by garbage workers or firefighters," boasted Dalton. "That's because we don't allow any collective bargaining with public employe unions and I think its a good idea."

With that, Bush with his Secret Service contingent and Dalton with his state police bodyguard, left the hall for another meeting.