Yes... check you're battery, when mine did that it reset then every time i laid it down and it would blacken right when it was ready to blacken out the screen would come back on. That wes with .75 spent 30 minutes on the phone waiting for VZW to tell me to do a battery pull and make sure it was holding in there well (a light shake will do with the back cover off) "thats what she said"
Maybe try the ol' business card between the battery and door trick? I've seen that work on other phones. I have a piece of business card between my battery and the phone to help with typing and my phone hasn't restarted when tapped. Maybe they're related.
If you have only had the device for a short time, I would definitely demand another. If you have had it for a while, then I would suggest that you complain to the CSR's and try and see if you can get a new one. But be nice, as if you are not, you will not get any help!! Good luck, and let us know what happens, lol!