I wouldn't have bought it until it was fixed. When my gf bought her car I told them I wanted a couple of things taken care of. She was approved and ready to buy but I told them we would wait until those things were fixed. They said "we will have them fixed by Thursday" (had to wait for the parts to come in) and when Thursday came it still was not done so we did not sign. They pulled the car in and fixed it that day and then we bought it.
I don't trust any dealerships to do anything for me once I drive off the lot because for the most part they are scum and when you're dealing with used cars you really don't have any options you're just screwed. Unless the car was such a steal that even with body blemish it was still good, I'd have not driven off in the truck or paid for it until it was how I wanted it. Honestly I'm surprised they have done this much for you. You must have drawn up a really good purchase agreement. Without question they had it reviewed to see if there was a way to get out of fixing it and obviously there was not. Good for you.
If it were me I would request a similar truck while this one was being worked on.