I hate to be the bearer of bad news but it sounds like you have a warped head. The gaskets used now are multi-layer steel. The days of the "blown head gasket" and the usual "symptoms" are over. That is classic symptom from the last few i've done....which is, happens after long drives. The head has to get superheated before that weak spot opens up enough to overcome the engines cooling ability. The longer you go without fixing it, the more frequent your overheating spells will be.

They may be reluctant to tell you what I just did because it sounds like hoooey.