No spots, but when my youngest is hurt/upset, he started doing something called 'breath holding' - a condition in which he forgets to breathe and actually passes out briefly. When this happens, his hemangioma (on his forehead) turns almost black. We joke that all the blood in his head is rushing to the H - his face gets pale, too. When he finally cries/breathes, the H deflates and gets all wrinkly as the red color comes back. It's alarming, to say the least, to witness it. But probably something along the same lines as what's happening to your son's H, maybe?
Me - Aimee - Spot on liver
Elliot, 9/20/06 - H on back (nearly gone)
Felix, 7/28/08 - H on forehead (in involution)
Taking the 'wait and see' approach, for now.