Is there some physiological reason for this?
Er, um...have you considered age?
Seriously though, after thinking about this for a bit, I figured there might be three things at work:
1. Age. You're not as young as you used to be, guy.
2. Dehydration: I think that does play into it. You dehydrate when you exercise, and drinking wine dehydrates you as well.
3. If you drink wine immediately after vigorous exercise, there might be a synergistic effect: exercise oxygenates the body, forces open the capillaries, etc. If you drink wine in that condition, it could be "going to your head" faster than it normally does because you've sped up your circulatory system.
Of course, I know nothing whatsoever about physiological effects of alcohol on the body in conjunction with vigorous exercise. That would require me to vigorously exercise. And, as my wife and doctor tell me on every possible occasion, I don't do that. Exercise, I mean. The wine part I've got down.