Technically, you should be okay... the dealer should close it at your documented previous price when your secured your order:
http://www.corvette7.com/forums/showthread.php?t=345508
From GM: (
We spoke with a representative from Chevrolet who told us that) “customer demand for both Stingray models and especially the Z51 has exceeded expectations and we are trying to meet that demand.” The Chevy representative added “Customers who have an order in the system are not subject to the price increase.... The bad news, unless you got an order already in the system or you buy an existing Stingray off a dealer’s lot, prices are going up to meet that demand head-on.”
I'd discuss and hold that to the dealership... perhaps get it in further writing too. Wouldn't hurt to ask...