Head Gasket Issues after coolant exchange

My wife had oil changed at a “national chain” automotive center recently. They also got her to have a coolant exchange done while she was there. The next day, she noticed a slight rough idle and thought it was bad gas from filling up after the service. The car sat for two more days (she was off work). Then when it was cranked after that, she noticed white smoke/sweet smell out of the tail pipe. We took it back to the place and they said “bad head gasket”. (The valves/heads/gasket were redone about 4 years ago due to a TSB related to valve issues.) Car has never run hot, been driven hard, does not leak any coolant, nor leak or burn any oil. The recent head gasket issues started only after the coolant exchange. Oh, the place that did the exchange told us: “Not our problem, because it was a routine maint. service and the symptoms were not present when the car left the shop.”

We’re having it moved to another local shop (the one that did the head/valve job) on Monday to let them look over it and get an estimate.

My question is: “Is it reasonable to think the recent head gasket issue is related to something occuring during to coolant exchange?”

I can see no way that a blown hedagasket can come from a properly done coolant exchange. I emphasize “properly done”. If, however, someone made a boo-boo and ran the engine at eth shop without having refilled the coolant, then they two may be related.

There’s no way to find out, however.

Let us know what the new shop says. We care.