Toyota Camry 2005: Coolant costing

I was surprised when my dealer recently informed me that the radiator on my 2005 Camry was showing signs of a possible future leak from the lower tank; evident by some staining similar to a water stain. The quote for the replacement was $530 including labour and coolant, which astounded me. As I bought it new, and it has been serviced by the same dealer, and has only done 36,000 km I asked the dealer to approach Toyota with the request to cover the cost. But Toyota will only cover half the cost of the radiator and coolant, thus the labour will have to be absorbed by me, to the amount of $340. Is this a common fault in this model, and do you think that Toyota should have covered the total cost?