General Fitness & Nutrition: Pain behind my right knee

I ride about 80-100 miles a week, give or take.  For a month or so I have been noticing some pain behing my right knee.  It seems to be the ligaments at the top of calf and the bottom of my hamstring (but mostly the top of my calf).  I don't notice it every time I ride, probably 60% of the time.  The pain is nothing major, but I know it is there.

 I have messed around with saddle height some and this seems  to be as good as I can get it.  If I go any higher, the pain increases.  I have a slight bend in the knee when at BDC but probably more of a bend than the pros.

 Any thoughts?  Being only in one leg is curious to me.