Thanks for the responses. In fairness, my description should have included that when I looked at my hand again on the turn, the players to my left (who were out of the hand) could have seen my cards. I wasn't deliberately showing them, and there was certainly no collusion. But I think that the Floor thought that this was a "show one, show all" issue - even though it was on the turn, and even though I mucked before the river. The Floor was a woman in her 40s/50s who I don't usually have interactions with. Thanks for your comments.