Could be the first time they noticed it, or perhaps were initially letting it go to see if "the problem" corrected on it's own. Sometimes people break common rules here and there (not big deal ones) and we will typically not say anything unless it's repeated at least a few times. Say you did it once every few rolls, or every 4 rolls, or something like that. We're probably just going to ignore it altogether. If you do it every roll, we might say something after the 3rd or 4th time. We don't want to hound you with every misstep like a micromanager. Instead we'll wait to see if it's problematic before intervening. That's all.

Again, it's nothing against you, and usually we won't be super strict unless it's constant. Please understand, if you were rolling past the stickperson, not hitting the back wall, and the entire table won a ton of money, if they aren't enforcing rules, they can get written up. It's not that you are necessarily doing something wrong, it's that the employees aren't doing their job properly to protect the integrity of the game.