This keeps happening to me. If it helps I am using a black 32GB iPhone 3GS with rogers, purplera1n RC2a and the following winterboard items in use; iTicker,Strong bad Email Notifier, Notifier Widget, 3D Fiction 3 Vwallpaper, Custom Rogers Carrier Logo, Spotlight Dialer, Chuck Norris Slider, Bolt Action Rifle lock sounds, Android Battery, Glasklart Alt Dock, Glasklart No Page Dots, Glasklart Visible SB Sta....?, User Wallpaper, Transparent Dock, Solid Status Bar, Black Navigation Bars, No Docked Icon Labels, No Undocked Icon Labels. In that order. If anyone else has some suggestions or this happen. Do note, a simple lock and unlock fixes it, not the end of the world, just gets annoying.