Thats about right, the psi increases as you go around. Just check them every time you come in. I have seen fluctuation from start point of 34 up to 38 when I came back.
They outside tread is not cut very deep. The outer on my rears were bald before the inner tread hit the wear bars. Now you get to listen to everyone tell you that your tires are bald :bored:. I hear it everytime I drive the car.
However, I can run a set of GY's at Sebring and not experience a tremendous amount of tire wear. However, take the same set of tires to Homestead or Palm Beach International and the way they cross cut the track surface is murder on these tires.
So even if you keep the PSI proper depending on how the track surface is cut will make a big difference.