The morning after the morning after

I've noticed something weird the past few months -- after I go to the gym one evening, I'm not sore the morning after, but the morning after that. Not that I'm a gym rat or anything, but I've been going to the gym off and on for a couple years now, and if I overdid it, I always felt it when I got up the next morning. The past few times when it's been two mornings after, well, I'm not sure what the deal is. It's not like I'm sitting on my butt all day or laying around in bed. Maybe it's just another fun part of getting older..