That is not supposed to happen when you only remove the caps.
It sound to me that they have been messed with and some parts are not put back together correctly.
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If he took the caps completely off one at a time, with the wheel still on and hanging, they can drop a little like that. It'd drop further by removing the left cap vs. The right cuz there's more play in the damper in the right fork. 6 inches sound like a lot, though.
I wouldn't have done that.