Since (I *think*) upgrading to Snow Leopard I sometimes experience delays of a few seconds between hitting a keyboard shortcut and the execution of scripts. When it happens, the FastScripts menu item icon is blue for the duration of the delay, then it goes back to black and the script runs.
The strange thing is that it doesn't happen all the time. After I invoke a script once, it usually triggers quickly after that first time for a short while.
I made a screen video:http://gallery.me.com/liyanage/100048
It's a bit hard to see because the menu bar is tiny, but you can see that the icon turns blue when I hit the shortcut, then it stays that way for several seconds, then the script runs (it resizes the window) and the icon turns black.