I think this just happens sometimes. I have a 2008 Macbook Pro (first 15" "unibody" model) and its user-replaceable battery pack started swelling after it got p

I think this just happens sometimes. I have a 2008 Macbook Pro (first 15" "unibody" model) and its user-replaceable battery pack started swelling after it got pretty old. I took it to the Apple Store and they said it's not uncommon for old batteries. I bought a new one, handed them the old one, and was on my way.