Based on several cases of people contacting AZ regarding their booking it seems that the fares will all be honored. In fact, one person was told that all fares were as they should be, except for the ICN fare which had tax/surcharges missing for june.

So the 540€ deals we're seeing are definately not mistakes, the 250€ deals to ICN just had a mistake with the first few fares on a brand new route. Seems 99% certain that all fares will be honored and it was/is just a great deal.