I have trawled through Meta for a while now looking at many questions (the search terms seem to mainly return questions where rep isn't awarded at all) - the closest I found was this:
As I use the site of an evening, I have noticed on many occasions that my tabs show a rep increase as if my answer was accepted - but when I refresh it shows that another answer was accepted. This is solved with a page refresh and doesn't bother me as such - just wondering if there is a bug somewhere in the code. This happens across all my browser tabs (I see the rep increase by 15) but if I hover over my login to get the activity hover thingy it displays my rep and accepted answers correctly.
I don't want to throw out my own red herring (it may be the only time that I notice it), but I think this might be only the case when the rep cap is hit for an evening.
This question isn't to complain or whine, just trying to help pin-point a bug in the code somewhere.