Thanks for the advice!

I haven't changed anything on my bike. And, yes, the pain appears 9 times out of 10 when I'm trucking it up a long hill. It subsides when the terrain levels (but is still a little sore), and will even tingle like pins and needles at times if I'm doing a lot of climbing. Normal, yes? The only time it really hurts when I'm off the bike is when I'm climbing stairs, which is a similar motion.

Anything I can do to strengthen/stretch/ help these muscles recover (just above the knee and also on the spot on the inside of the knee directly across from where the lower IT band attaches)?