my still-new-to-me (owned for about 7 months) 06 Outback has developed an apparent headgasket leak.

Spoke to the dealer to get it looked at, so not confirmed yet. The car has done about 160k, dealer serviced it's whole life and hasn't been overheated as far as I know.
The leak (really a fast seep at this stage) is at the back of the passenger-side head, i.e. right-hand side as you face the car. It doesn't seem to be losing coolant or getting oil into the cooling system (yet...)
Is this 'normal' in an Outback of this vintage and mileage, and how much would I be looking at for repairs?
The dealer has given an estimate of $2500 to replace both headgaskets and timing belt.
Thanks in advance for any thoughts!