Clocking In Late

I have been having problems with a co-worker who cannot seem to make it to work on time. Normally I wouldn't have a problem, but he is my relief and if he is late, that usually means I have to punch out late. And I wouldn't mind punching out late if I didn't get 40 hours a week. But me getting overtime sometimes results in me getting yelled at. Also it seems that this individual does not have any remorse for his tardiness. So I spent a lot of time fussing about this guy this week. And karma got me because I had trouble getting to work on time this week. Yesterday I punched in six minutes late, and today I punched in four minutes late. This kind of tardiness irritates the hell out of me. The lesson here is that I should not have spent so much time fussing about and judging this guy about his tardiness. Because then I ended up being the late one.