iOS framerate drops (after adjusting volume)

I’ve noticed that all the oF apps I have on my iPad 2 and iPhone 4 (several of my own, and the box2D test app) all drop from 60->45ish FPS for a second when the volume display fades away (the display shown after using the hardware volume controls).

Has anyone else experienced this, and can shed some info on possible solutions? It does not happen in any other, non-oF app that I’ve noticed.

Also, my apps seem to have framerate hitches occasionally, most often when they have just been started. Very short FPS drops, just a frame each, every once in a while. I’m not sure if it’s related to the volume display issue or not.