Ooooohhh, let me guess. You were inserting the airlock into the hole in the bucket lid, and the grommet descended into the icy depths. You immediately plunged your arm into the wort to retrieve said grommet. Triumphantly, you gazed upon the dripping, collared device. Then doubt began to arise. "What tiny, hellish fiends have I unleashed upon my wort?" you cried. Happens to everyone. No worries.
What he said. I don't think anyone can tell you definitely either way. Even if it does get infected, it could be from something else. It is a waiting game.
Everyone's concerned about the wort — what about his hand? I do hope his shot records are up to date.
This. As long as it was your hand I wouldn't worry about it, and have a homebrew. If it wasn't your hand I would consider moving to mexico....