same here..i did a century last sunday and after got back home, my kneecap hurts like hell. It seems the pain comes beneath the kneecap more. But obviously, i heard some "squeaky" sound when i squat down and stand up again. Till today, the pain is hell, especially when im inside air-conditioned room or when i drink cold/iced drinks. I should go to doctor to check it out soon. Im off the bike for this whole week for sure. Damn sad about this. No cycling = No life...