That's weird... me on the other hand level 16; and have had a handful of random encounters... the best one would be when I was roaming around in Riverwood. It kept flying from the roof of one house to another until it finally decided to land near the lumber mill. I also had one which was not hostile at all and was like a vulture and kept circling around Volundruun (did I spell it correctly?). Only when I went up some vantage point and shot at it with an arrow did it notice me. Maybe you'd want to back up your save and then do a fresh install? Random dragon encounters are fun! :)
