Part of touchless controls I believe. Mine works great, shows me what's up when I take it out of my pocket, never pocket dialed or anything else while in there.
I have had an occasional pocket dial with the Maxx on touchless control, and more than the occasional unintentional voice command response. It's embarrassing when your crotch area starts speaking out loud in public. LOL
Every now and then I'll pull mine out of the pocket and it is on voice command screen or Google Now; and I'm pretty sure I never said the command. But at least it has never pocket dialed.
The proximity sensor (light sensor?) acts as a pocket mode surrogate. However, Touchless Control is always active and may respond to voice commands even in "pocket mode."