I had the phone plugged into the computer transferring things from my hero and was trying to access the card from the phone at the same time. Didn't realize I couldn't do that. Flame away.
I did have an issue with one video today. It won't play back. (It was a really cute one of my daughter too!) But after that one it worked fine, so I am assuming it was some other glitch as the SD card issue seemed to get worse until rebooted.