new #@$^!! problem

Well this one is kind of funny and unusual....bought me a 92 4x4 with a rebuilt engine under warranty still. Had a local shop check it out first, and they found only a couple suspension problems, so I gave the owner the money and told the shop to fix it. They start it up and drive it onto the lift and it's burning coolant all of a sudden. They theorize pressurizing the cooling system while testing may have blown an already weak head gasket or something. And if the heat tabs are melted the engine rebuilder won't honor the warranty. Somehow I feel vaguely if I might have gotten screwed just a touch here somehow although it will be interesting to see about them heat tabs. Any comments on this one?