Today at around 14:00 an answer from me was accepted and my reputation showed 745.
4 hours later I checked again and my rep was back at 730. I checked my reputation overview but there was nothing like -15 today.
It gets better, I added the values from my reputation overview and the result is 735 (+1 from the start would be a rep of 736).
Could it be that an answer has been unaccepted and this is not reflected in the reputation overview? What is now correct?