That glob is the seam caulk. They get sloppy with it sometimes. In areas where seams meet like the rear quarter panel and rear panel the seam has auto body caulk. when the body is painted the paint covers everything. Even excess body caulk.
It ain't easy being cheesy:
Sometimes I make decisions like famous people.
George Armstrong Custer "lets go over that hill, I think those are friendly indians!"
Titanic's Captain Smith "What icebergs? Full speed ahead!"