I'm taking part of today and tomorrow off. On Tuesday I asked my direct report to cover something for me this afternoon and she said "No, I plan to call in sick day that day." I asked if she was ok and she said she was fine. I cocked my head and waited for her to elaborate with something like "medical appointment" but she didn't. I was so surprised she thought her statement was ok that I didn't know how to respond.

I was (actually) sick yesterday and didn't get to circle back with her.

I know there are legitimate reasons you could know in advance that you need a sick day. And there are a lot of questions you can't ask about sick days. Am I being a push over if I don't press why she was casually dropping that she'll be calling in sick? Or is it reasonable to assume a mostly responsible employee has a legit reason and wasn't flaunting that she was playing hooky?