WHETHER IT WAS the heat, the pollen count or the political winds that did it, Prince George's County has just seen two of its most prominent dyed-in-the-wool TRIM supporters get off their favorite bandwagon: all of a sudden, county council members Sue V. Mills and Anthony Cicoria are proposing an end to the four-year-old dollar-limit freeze on property tax revenues, without even waiting for the report of a council-appointed citizen task force that is reviewing the county's financial options.

You did have to wonder how many years might go by before the TRIM die-hards would cave in and recognize the inevitable obsolescence of the amendment as enacted. So give Mrs. Mills and Mr. Cicoria at least partial credit for Math I, but hold the applause--their proposed modification is little more than the minimum that any reasonable legislator would consider. Under TRIM (Tax Reform Initiative by Marylanders), the county may collect no more than the amount of property tax received in 1979, which is about $143.9 million. The Cicoria-Mills bill introduced Tuesday would allow the county to raise the ceiling annually by the amount of property tax on new development--which TRIM critics have suggested all along as the least that should be done.

But given the voters' reaffirmation of TRIM last time around, most council members, as well as County Executive Parris Glendening, had decided that a thorough but prompt look at finances should be conducted before trying another modification. That is what led the council majority to appoint its task force and Mr. Glendening to select another group, headed by a former Chamber of Commerce president, to examine changes in TRIM. But hear the new Mrs. Mills telling chairman Frank Casula, "You know as well as I do that the purpose of these task forces is to cause delay."

Nine times out of 10, that's true. But after years of insistence on the part of Mrs. Mills and, as it has turned out, a majority of the voters, that TRIM was just right as is, thoughtful politicians turned to the review idea as a fair approach to any change. That's fair enough, if the converts can only contain their zeal for change.