Not really, because there isn't any engineering reason for not leaning below 3000ft.
If it's in the POH, it's because somebody has made it up.
Is there really a Lyco or Conti engine manual (I mean an engine manual, not an aircraft manual) which prohibits leaning below 3000ft? I've never seen such a thing.
Sure it isn't a club/school operating rule, perhaps inserted into the POH to make it look more official? Much more likely.