Not sure what is going on here. Im lvl 35 and prior to getting the 1.3 patch I use to come across dragons here and there. It seemed to be just the right amount of encounters. Now I can't seem to find any dragons. I purposely ran across the whole map east to west, west to east, and not 1 encounter. So I said heck with it, and just went back to playing. Lvl 38 now and still no dragons

Have you tried checking in their bases like http://elderscrolls.wikia.com/wiki/Skyborn_Altar, http://elderscrolls.wikia.com/wiki/Shearpoint, http://elderscrolls.wikia.com/wiki/Mount_Anthor, http://elderscrolls.wikia.com/wiki/Eldersblood_Peak, http://elderscrolls.wikia.com/wiki/Northwind_Summit, http://elderscrolls.wikia.com/wiki/Ancient%27s_Ascent and http://elderscrolls.wikia.com/wiki/Lost_Tongue_Overlook... Even if you killed the dragon at some point, they respawn at certain times..

I'm having the exact same problem. I had a character which I took to lvl 30 and ran into several random spawn dragons.

I rerolled and have a new character. He's now lvl 23 and I haven't met a single random spawn dragon. I don't think it's a patch problem because up until yesterday I had vanilla. I only patched today. Been on the bug forum and found this thread, so it's not just us:

http://www.gamesas.com/topic/1327454-second-character-no-random-dragon-encounters/

POst on there...maybe someone at Bethesda will read it...maybe

If you talk to delpine but you dont start her quests, I think random dragons get turned off until you get past a certain point in her quest chain.

Of course, if that isnt a state you are in, your issue may be for a different reason.

This is true. If you have the quest "A Blade in the Dark" active there will be no more dragons until you finish it and get the next part of the main quest.