You probably didn't apply the paste correctly. Too little or too much can cause more heat. You don't need much at all when applying thermal paste. Try redoing it and pull it off. There should be a very thin layer on the GPU and HSF when you pull it apart. If there's a lot gobbed up off the side of the GPU, there's too much. If there isn't enough covering the GPU then there isn't enough.
Before re-applying don't forget to clean with some isopropyl alcohol and a lint-free cloth or coffee filter before applying new.
I've seen it already, and it's the perfect amount, with just a bit on the edges.