I am not seeing the pictures yet, they have to be approved by the moderator. But assuming the swelling is obvious, I would be looking for a new adapter. If the system is under warranty (I have to believe the warranty period is over), call Dell tech support for your region. I assume you mean the adapter and not the actual battery itself?
As for why, it could be overheating.
Instead of uploading the photos and waiting for mod approval here, can you make image mirror links from Imgur?
Just copy/paste the link in the post. Don't wrap it in [IMG] tags.
I'm actually not seeing the bloating, but it could be just due to the picture.
The AC Adapter may need a replacement just to be safe. If the system is under warranty, please send me a private message with the Service Tag so I can review your case.
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