I wouldn't worry about it. The "check engine light" came on for a reason. When the light is on there may be no symptoms with the way the vehicle runs or operates. This is quite common with the strategy for turning on the light. The dealership is right when it says the light comes on for more then 400 reasons.
Based on what you said there likely was a Diagnostic Trouble Code (DTC) active or stored. They performed the appropriate tests for the code which revealed nothing was wrong. In that case the problem was either a non-issue or intermittent.
Generally when a check engine light is diagnosed the DTC should be recorded in the cause section of the repair order so the customer is informed of the malfunction that existed. Hope this helps. If you have anymore questions don't hesitate to ask again.
Based on what you said there likely was a Diagnostic Trouble Code (DTC) active or stored. They performed the appropriate tests for the code which revealed nothing was wrong. In that case the problem was either a non-issue or intermittent.
Generally when a check engine light is diagnosed the DTC should be recorded in the cause section of the repair order so the customer is informed of the malfunction that existed. Hope this helps. If you have anymore questions don't hesitate to ask again.