Dealers definitely like to inflate prices and replace unnecessary parts. But, usually on the customers dime. I highly doubt they'd be willing to make a few thousand at the risk of pissing off BMWNA with unnecessary warranty claims.

Like everything, it'll likely depend on your relationship with the dealer. At your mileage there shouldn't be too much. But the usual would be the cooling system...radiator and water pump. Other things to check would likely be gaskets...specifically valve cover. You do have a CPO, so I wouldn't worry too much.