Prolonged QT interval is a delay between the electrical excitation (or depolarization) and relaxation (repolarization) of the ventricles of the heart. The most common cause is drug-induced. There are a number of short-acting benzodiazapines that will result in a prolonged QT interval, as well as several other medications. This is nothing to worry about in the absence of pre-existing symptoms.  

As I've stated before, if you're relying upon the computer's interpretation of the ECG, then you're headed for problems because it only knows what it reads, not "why" it's being read that way. You should never rely upon a computer to provide a diagnosis or interpretation, but rather only data output.

You'll be just fine.

Best regards and Good Health