In #9064 (Mac OS X 10.6.8) the selection highlight color gets more transparent (?) sometimes. After focussing TextMate 2 the color is correct, when changing to another Tab, the color changes. If you go back to your original tab it shows the same lighter color there to. When you focus another application and go back to TextMate it shows the original (more opaque) color again.
Regards Jannes