1. Are you 100% sure didn't summon ANYTHING this turn?
2. Are you sure you didnt used a skill that forbids you from special summoning (lets say Balance)?
3. Are you sure you had resources in deck/hand/field to use this card (red eyes monster and a warrior??
4. Are you sure your opponent didnt had a monster to interrupt you?
Well, personally, I am 100% sure you are mistaken.