Had a similar experience at a bar once. The bartender set the glass down on the bar in front of me, took my $$ and turned around to the cash register to make change. There was a "click" and the glass split in two vertically, spewing the contents all over the bar. Most glass has a lot of internal residual stress from cooling from forming temperature. A small nick or flaw in the right location coupled with thermal shock can do strange things.
Primary: , Boddington's Clone, Mirror Pond w/Marris Otter
Bottled: Fullers ESB Clone
Kegged: Mirror Pond Clone
Drinking: BM's Kona Fire Rock, Dead Guy Clone, Alaskan Amber Alt Clone, Firestone DBA Clone, Magnum/Crystal IPA
Next up: Burton IPA