Crash while using iPod App iPhone 4

Sometimes, while Im listening to a podcast and press the home button to wake up the screen, my iPhone 4 momentarily shows the Apple logo and restarts. Its much quicker than a regular reboot though. Does anyone know why this happens? Is it just a regular crash? Ive only noticed this happening since the 4.3 update.
Everything else with my phone seems to be working fine.
iMac 20-inch 2.66GHz, iPhone 4 Mac OS X (10.6)