The Baltimore Orioles have mailed out $60,000 worth of bonus checks to Jim Palmer, Ken Singleton, Mike Flanagan and Rudy May - but that is some string the baseball club attached: notification of grievances to be filed to try to reclaim the money.

The four players two weeks ago instituted grievances against the Orioles, claiming general manager Hank Peters had not lived up to the "significant contribution" clauses in their contracts. They said it entitled them to bonuses - and Marvin Miller, players association exec, said if they didn't get 'em, the union might find legal means of making the players free agents.

Hence the Orile countermove. "It's obvious (why)," said Miller. "They didn't want to gamble on a possible termination of contract." Palmer, Singleton and Flanagan are under contract through 1980, '81 and '81, respectively.

May, an 18-game winner, was traded to Montreal a few weeks ago. Flanagan was not told exactly what goals he had to reach to collect a bonus, so the lefty could be in good shape to hold onto it after coming from nowhere to win 15, including 13 of his last 15 decisions. But revelation: Singleton and Palmer, indeed, failed to reach Peters' goals.

Singleton merely hit .328, 24 HR, 99 RBI in a strong bid for American League MVP laurels while Palmer was a 20-game winner with 2.91 ERA. But Peters had told Singleton by letter, he would make a "significant contribution" if he batted .330, hit 30 homers or batted in 110 runs; and Palmer, to tack extra money onto his already rich salary, needed 22 victories, 2.50 earned run average or another Cy Young Award. Flops!

Now, hold the phone: side deals listing qualitative criteria aren't kosher under basball law.

Oh what a tangled web.