Mine done exactly that. it didnt open the shutter. so i contacted apple under the warranty and they replaced it for my with a brand new iPhone 3GS 32GB black
Try restarting the iPhone by holding the Sleep/Wake button until the red slider appears> then slide to turn off> and turn the iPhone back on by pressing the Sleep/Wake again, as described on page 46 of the iPhone User Guide.
http://manuals.info.apple.com/enus/iPhone_UserGuide.pdf
Restarting/restoring might fix it temporarily, but it most likely will start doing it again-could be a week, could be a month, but it will re-occur. It's a hardware issue according to Apple- my 2 month old GS stated doing it when it was only 3 weeks out of the box, took it to Apple and they replaced it. I wouldn't waste your time doing a DFU, and losing everything- just take it the Genius Bar and let them do the DFU, that way when it doesn't work , and they(hopefully) exchange your phone, you will still have your b/u to re install on the new phone.