been having a little bit of knee pain lately. it's not during the ride, but always after the ride, sometimes a day after, maybe even two. I can feel it if I'm getting up from a sofa and using my knees. I can never feel it on the bike while I'm pedaling, but have felt it after a long hard ride, and then standing up to pedal home. the feeling is dispersed throughout the joint. Is this a problem or no?