After moderate exercise my rt knee occasionally swells a little and gets stiff. rest and ice usually resolve it in a few days but it reoccurs occasionally. should i be concerned?

Exercise: shouldn't do that. So, evaluation by a trainer to avoid the impact amount that is causing inflammaiton needs to be done certainly. And certainly you don't need a joint replacement. Evaluation by practically any doctor can determine if there is significant joint problems without an MRI.

See physician: If this is a recurring problem( and it sounds like it is) see your physician for a referral if needed to an orthopedist. A history and thorough physical exam by a good ORS should yield a presumptive diagnosis(tendinitis , bursitis, meniscal tear, etc.)Xrays of the knee and MRI( if indicated may confirm. Best of Luck!