Amazing recovery?

Went for a 5km run on the treadmill this morning. I took it fairly easy, taking 25min to finish. At the start my legs felt great. I thought "Wow, I've recovered really well, what was I thinking earlier in the week". Then the legs started to get sorer and sorer. After 4km, they didn't get any worse. The foot didn't feel bad at all, but it was a little sore after the run. Seems OK now. I guess the recovery isn't as amazing as I thought, although I can't believe I could barely walk on Monday. The cold is hanging around too.