Taylor Swift DJ Admits Touching But no Ass Grab

The radio DJ accused of grabbing Taylor Swift's bare ass while posing for a photo with her has spoken for the first time, and has a pretty handy explanation of what went down ... for him.

DJ David Mueller gave his account of the infamous alleged groping to a Detroit's "Mojo in the Morning" show Tuesday -- he says there was a touching of Tay ... but it was accidental and harmless.

Mueller claims his hand was never open and sounds pretty pissed over allegations he touched her bare bottom. Take a look at the pic ... do you buy David's story?