I came across this phrase in a book I was reading, and it struck me as incorrect: "reexamine his assumptions"

The reason it seems wrong to me is because I see an assumption as a belief acquired without any examination, based on surface observation or information, and inherently unexamined. Therefore, one would need to examine the assumptions, after which any belief retained would no longer be an assumption. For some reason I can't come up with the term for this type of phrase, so feel free to let me know about that, too! :0)