Mine was like that. So badly swollen the touchpad was almost impossible to press. I replaced the battery myself and it really wasn't bad at all. Less than an hour roundtrip using the "string method" (I saw it on a YouTube video) to slice through the tape they use to glue the battery down. The worst part was trying to clean off the old adhesive before putting in the new battery. This method is really non-invasive because you don't have to pull off a bunch of other parts.

I would just show up at Apple with it. I had gotten a product from them completely replaced long after the 1 year warranty was due lol

I have two that are that time frame, one with a swollen battery as well, neither apply.