99 Expedition XLT 4.6 liter

My expedition's left head gasket went out at 90,000 miles and was repaired by the local Ford dealership under extended warranty at a stated cost to them of about $1200. Now, at 120,000 miles the right head gasket is seeping oil and needs replacing according to the Ford dealership. Can someone tell me if I probably need to change the gasket right away and is $1200 a fair price to change a head gasket? Thanks!
Ranger Ric

Check with an independent shop ask for the flat rate time. Multiply this by the hourly rate. Call a parts store and check a gasket set for the head.
Don't run with a leaking head as anti freeze will take out the bearings in the motor. This is big money.