Been there and done that: http://www.bbq-brethren.com/forum/sh...mp+butts+smell
The smelly butts that I had turned out to be from a box that had expired 3 months prior. No idea what it was doing at the grocer's cold storage. I'm thinking that, in your case, a week is a bit long for non-frozen butts.
Edit: The linked thread isn't what I was shooting for. I had another thread going with some really smelly butts. Either way, I tossed them.