My new stock Maxx that I got last Thursday has been doing the same thing...I noticed the phone would wake up to the lock screen right while it was sitting on the table with no one around. That night, I updated to ICS hoping that would improve things...nothing doing...
I tried two hard resets, three soft resets, setting up Smart Actions, update kernal info, turning off all GPS, using wifi only, using 3G only (we don't have 4G here yet) The screen kept coming on randomly no matter what I did...80% of my battery usage was the screen....I did NOT buy a Maxx to have the battery die because of the random lock screen "wake ups".
To attempt to fix before returning...I troubleshooted with the store I purchased it from, the carrier & Motorola and finally picked up a new one today.
So far, so good...by now, the old one would have turned itself on...
Here's keeping my fingers crossed....
-JT