I recently picked up a six pack of this and it tastes stale. It wasn't sitting in any bright light, so would this most likely be an issue of it being re-refrigerated? I've had enough Summer Ale already since it became available to know it's not my imagination, haha.
I think I heard a few rumors here and there on BeerAdvocate about a bad Sam Adams Summer Ale batch. Sam Adams is always very good about handling old/bad beer. Like thepaintedman said give them a call or call the distributor.