I see you sped it up and already discovered it was an Infinity. I have noticed numerous other players stating similar anomalies, while trying for both Quetzel and Crusader. It seems as though TL has been messing with the breeding rules again, as other problems have been occurring as well (like no black possibilities from Diamond +Zodiac/Champion)....But of course they haven't made any sort of announcement explaining the rule changes...
Anywho, congrats on your unexpected Infinity dragon!