In both the places I've worked, it's a common joke anyone says when somebody leaves. everybody laughs and nobody gets offended. It doesn't mean anything.
It's like if you're on the bus and someone's sitting really close. Some people would say "Excuse me, you're too close", but others would jokingly say "Little close, aren't you?", but the meaning is the same - Move.
That kind of thing only works as a joke when it's about an obviously late hour (i.e. well past the norms of the company). If someone stays until 9pm to put out some fire and then people joke about working a half day, its obvious that there's no underlying meaning to that, since the leaving hour is well past the established norms
I would say this applies to any value.
Also, I'd probably worry that such frequent jokes walk a very fine line towards passive aggressive behavior (again, such jokes just won't exist where there is no expectation).
obviously I don't know your workplace, so there's a good possibility no one gets offended, but just pointing out there's different interpretations of such actions, and just because no one's saying anything doesn't mean it's not happening...
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