Sooooo another update.
I got my device switched out about a week ago.
I had in-pocket detection activated on the original device, but have never turned it on on the new one.
TWICE TODAY I have had the phone freeze like this....
This is very much starting to concern me...
I havent had my phone reboot or lock up once. If you re-installed all of the same apps as your other device, one of them may be the problem. I would try uninstalling all of your non-stock apps and see if it still does it.