I can't shed any more light on that one, but I do have a similar story. When the guys played the West Hartford Ballroom on 3/21/87, somebody threw a fairly full beer can that hit Grant's drum kit during "You're A Soldier". He stopped playing/singing briefly then angrily persevered through the rest of the song (although he did yell "Fuck you!" during the instrumental part in the middle).
After the song ended, he got out from behind the kit and yelled into one of the front mics "I don't know which one of you sons of bitches did that, but I'm going to find me some new cymbals!" (if I'm remembering the verbiage correctly). He stormed off the stage briefly, then came back and launched into "Could You Be the One".
After that was "Too Much Spice" and Grant, at the height of his cleverness, changed the refrain to "And you're threatening my life, with Miller Lite".
It's all there if you listen to the recording of that show, which I believe has circulated.
The epilogue to the story is that I later met the guy who threw the beer. He lived in my dorm at UConn during my freshman year. Long story short, he essentially said that he did it because the Warehouse material wasn't punk enough and, therefore, sucked.
-Mike Morris