Although no help to you this is the first report I've seen, so does not appear to be a common failure.

 

No probably not a common failure but a failure it is at 44k. And $500 later I have a new muffler.

 

did whomever did the replacement offer a reason for the seam coming apart???...corrosion?...backfire???

Bill

 

Subaru informed me that excessive exposure to water and dirt/gravel were the likely culprits.