I noticed that every time I did a coffee rinse that I shed like crazy.  The last time there was hair all over my shoulders.  This is not normal for me and I was wondering if the acidity in the coffee could possibly be causing the weaker/damaged hairs to break.  Any ideas?

I agree with bikerbraid; there's probably some other factor that's causing the shedding. I'm no chemist, but my understanding has always been that the acidity is good for one's hair (to a certain point, at least - but coffee shouldn't be nearly acidic enough to cause a problem).

If anything, the extra shedding is probably just due to applying more stress to your hair while applying the rinse. The same thing happened to me the first couple times I used coffee. I'v found that mixing it with a conditioner really helps.