I'd recommend that you read the code(s) that set off the light. We can guess all day but that won't help you.

It sounds to me that, very likely, what the dealer was saying is that the system failed the pressurization test that it does periodically. if that is the case, it may never come back. My Graphite would throw that code maybe once a YEAR. I never figured out what it was seeing.

So, what code(s) were stored that caused the Check Engine light to come on?

Did you know that you can buy very cheap OBDII readers that you can read your own codes with? Also, most any auto parts store will read codes for you.

The purpose of the Check Engine light is to tell you that the system has stored a code or codes. By reading the codes(s) you will know what the ECM is seeing and you can act accordingly.