technical foul at end of game

[mngoose33]

This came up in an intermural game tonight...hopefully someone can clue me in. The score's tied at the end of regulation, A1 drives to the basket but fails to get a shot off before the horn. B1 fouls A1, but foul is obviously after the horn and not flagrant or excessive. A1 is upset and curses, drawing a technical foul (again, technical occurs AFTER time has expired). Refs award 2 FTs (one is successful), but insist that since technical occured after the clock expired, the game still goes to OT with Team B leading by 1 point at tip-off. This seems wrong to me, but I wasn't sure and didn't argue. The call didn't effect the final outcome, but I'm still interested in the rule.