Throws My two cents in....

First of all, your question is one that is NOT a silly question- it is in fact a good one.
As you can see from the responses.... there may not be a solid ruling on this but one thing is certain... bdsm is all about power exchange and trust... its also about consent...

WHAT DOES IT MEAN when a dominant says something ( in this case agrees to a limit) and then.... ignores it?... What does it say about Him/Her? and course the next question is... do you still wish to be associated with One like that? Do you still feel comfortable giving Him/Her your trust?

Is the answer to pick up your bags and move on? Personally, I would say....NO... I think the answer is...... as is ALWAYS the case in this lifestyle, if you have an issue, you should bring it to your Dominant, place it in His lap and see how He responds. If His response doesnt cut it, then its time to make that decision.. "should I stay or should I go now"