I haven't been hearing any sounds for notifications for the last two days for texts, emails, or twidroid. Then just now, I plugged my phone into the usb cable to upload some mp3s, and after mounting the sd card my phone flashed the light on the home/menu/back keys several times and then spent about 10 seconds playing my notification tones over and over, presumably playing the tones it didn't play earlier.

It was so weird, I laughed, and thought I'd share it here.