CBP is the same way, they can request a doctors note for one day but they have to ask for it when they grant the sick leave. This means if you call in for sick leave and they say OK approved then they can't later ask for a doctors note but if you call in they have the right to ask for one up front. It sucks but that's the way it is.. ast least here.
I am a Paladin, like the warriors of old, ready to stand on the line to keep others safe... A Sheep Dog, ready to protect the herd from advancing wolves!