That area is prone to body flex also. There is a seam in that area for the roof to quarter panel as was said before if there is a rust bubble there, likely has a much worse rust problem behind it.
GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.