When I bought my Maxx on the 30th at a corporate store, the guy said there where 3 left, I got one, he got one and another employee. Who knows if it was true though. Their employees are not trained very well. My brother went in on Friday (I had to go with him) to pick up the LG G2. The sales lady knew nothing about it.
My brother patiently taught her about the phone (wireless charging a VZW exclusive, 2 tap screen to unlock, etc). He also asked for a quick window case. She said "this phone doesn't have one". My brother corrected her and she finally brought one out. They didn't even have an LG G2 on display.
Sorry for OT.
I think it's probably a combination of of low forecast (knowing the G2, Note 3 and iPhone 5s where all coming) plus more demand for the beast battery than they expected.
Droid Maxx...Battery Life!