Why would my legs start to sweat more than my upper body?

First of all, IANLFMA, this is much more of a curiosity than a problem. And google and yahoo were no help at all.

Here’s what happens. For the last two or three months I’ve had occasional mild insomnia - wake up an hour early two or three times a week. No big deal, not that unusual for me. But the interesting thing is that almost every time it happens my legs are sweating pretty profusely when I wake up while my upper body stays totally dry. I sleep in a T shirt and underwear, no pajama bottoms. And my legs pretty much continue sweating until I get out of bed and get started with my day. And it’s not completely out of control. If I kick off the sheet and lay there in an air conditioned room the sweating stops. But the interesting thing and totally unique for me is that there’s such a discrepancy between my upper and lower body. Is this a normal pattern? Any ideas?