Is an ECM replacement on '11 Ford Territory a major problem?

I am about to have a face-to-face meeting with a reputable dealer about my 2011 Ford Territory Titanium. I've had it 18 months and travelled around 35,000 km in it since. About two months ago, it went into limp mode for no reason on a busy motorway. I've had it at the dealer and have received it back after five weeks, and they have replaced the ECM. My concern is that I have purchased this vehicle for touring with our caravan and now have grave concerns that it will do it again. I want to know if an ECM replacement is a major item to have had replaced in the car? I have owned cars for 25 years and have never had an issue like this, even in my more modern vehicles.