Pre- Delivery Vehicle Damage Question

[08WhtX5]

Looking for some input:

Trading in my 2004 Mercedes S430 for X5 - Bought brand new from dealer.

Salesman comes in after inspecting my trade and asks who did the paint work.

I said the car was never hit , not a scratch or a ding 23K miles. He tells me the entire car was repainted. He shows me the tell tale signs and whips out his "paint meter". Tells me no body filler but car was definately repainted. Now the BMW/Mercedes part of one dealer family so I ask him to call MB and find out what the story is. Comes back in and says must have been "port" damage the paint work is to good to be body shop.

Spoke to General Manager at MB today and showed him the car. He didnt say much but agreed the car was re-painted but claims the dealership has no knowledge and no record of paint work.
They upped the trade in allowance from 30 - $31,500 but I still feel I got taken on original purchase and probably wouldnt have taken a $78K car that had just been repainted without a substainal discount. I'm sure I'm getting popped for it now at trade in time.

Question - should I let it go or push harder? It is a 3 year old car now but I just cant shake the feeling that i got screwed and here I am buying another car from them. I would cancel the order but I do like the BMW rep and car is scheduled for week 40 build.