A search turned up nothing, so I hope this isn't a subject covered ad nauseam... I noticed that when I was latching the top recently the handle was not locking away in it's little cubby, so upon further inspection I realized that there is a little roll (or spring) pin that keeps the handle in place that had worked it's way slightly loose. Three taps with a small hammer and was right again.
I live in southern California, so have the luxury of only driving my GXP in good weather, which means I almost NEVER have the top up, so this may have been a problem for a while that I just noticed.
I bring this up only because if yours is also working its way loose, you may want to give it a few taps as well. My guess is that putting the handle back on and replacing the pin could be tricky.