I haven't rollerbladed since I was a kid. If you enjoy doing it and it gets you exercising I wouldn't stop. Mostly likely you're really sore from the sweeping motion used to drive yourself forward. I can't think of too many other normal daily activities that involve that same motion, so you activated muscles that aren't normally used that much.
As far as surfing I wouldn't give that up either
It has to be one of the most relaxing/enjoyable activities I've ever done. At one point I could've been considered a surf bum, but these damn adult responsibilities limit my water time now :p