So here's a question:
Say you get sick unexpectedly and have to take several days off from work. Like, a whole week off. Which come out of your sick days, but still, you're out for a week and everyone has to cover for you.
A couple of weeks later, you have a week of vacation time scheduled, during which time you don't have any travel plans. Should you cut back on your vacation time, due to inconveniencing everyone when you were sick?
I say you shouldn't. But other people I know seem to mumble under their breath differently.