I agree with LucasM. When I did that timesheet, I had similar problems. My numbers just didn't quite add up. Like you said, nothing huge, but not exactly right either. I went through my logbook from day 1 and found and corrected several minor errors. It took many many boring hours to do, but everything added up in the end, and I felt much more satisfied submitting it that way. No sense risking a chance at a phenominal job over a couple careless mistakes!