The 26-year-old has been named in previous Scotland squads by Gordon Strachan but was omitted for the trip to Wembley, a decision which surprised McCoist.
He said: "Lee has done really well so far this season and I'm a little bit disappointed he's not in the squad. I'm sure he'll be a little bit disappointed too.
"Gordon has picked his squad though and we have to respect that.
"I'd be very hopeful that if Lee keeps performing the way he is, it won't be long before he's back in there. That's what he has got to aim for.
"Lee's attitude, as everyone can see, is absolutely first class and it's how he reacts to the disappointment of being left out that's important."