her credit score and history were probably improving that whole time
Until she paid it off, at which point it dropped.
Maybe her score went up 300 points over the years of that loan
Maybe, but I highly doubt it. And 35 points is a big drop when you're already in the 700-range. That can be worth a quarter point on a mortgage loan, which will end up costing you tens of thousands of dollars over the life of the note.