Did baseball change the pitcher's rule re: going to mouth?

I wanted to find this out all summer and kept forgetting to post it. It seems that this year, pitchers put their hands to their mouths any old time while on the mound. My understanding was that they were permitted to do that but not while on the rubber, or if the ump determined that weather conditions should allow for it. But this year, it seemed to be common and not related to where the pitcher was standing nor to the weather. Did that rule change? Did the umps decide not to enforce the old rule? Are my observations incorrect? (I guess this question could get tossed to The Game Room, but since I do seek a factual answer I’m posting here.)

Moderator Action

Even though this is a factual question, since it concerns the rules of the game it does belong in the Game Room. I’ll pitch it on over there for you.

Moving thread from General Questions to The Game Room.

Now dry off your keyboard.

A new rule — some say a “clarification” of an old rule — was established at the beginning of the 2010 Major League season. Early on, some said it was poorly explained.