I've been running for a while and now my kbees pop every once and awhile?

Keep alert for pain: Noises in the joints, especially the knees, can be quite disturbing and cause concern. Often, these noises are not indicative of any underlying problem. Knee cracking and popping usually often persists for years without any real problem developing. If there is no pain with cracks or pops, you can assume it is being caused by the soft tissue in the knee joint. Pain may signal arthritis or injury.

OK if no pain: You should be more concerned if you have pain, then you should have an evaluation by a qualified physician, I hope this helps,