If he does that in an interview with an NFL team, its probably a red flag. The thing is all these guys prepare for this and Geno should have been expecting that.
Now all a red flag means is that further investigation is required. Something like that happens in an interview with a guy you are considering taking early at that position and now you check out some other things. Maybe you have a question for other WV prospects to shed more light on Smith's knowledge of the playbook. You press his college coaches a bit on the issue. You go back through the game tape to see if he was confused by the same blitz or coverage multiple times.
Before you die Lonestar, there is something you should know... I am your father's brother's nephew's cousin's former roomate.