I work downtown, at Heinz Hall (1 block from the Benedum)! There is a Qdoba around the corner where the manager is VERY celiac-savvy--his wife has celiac! Practically everything there is safe, as long as you avoid the tortillas and a couple of other things, and he knows to change gloves, use a clean work surface, etc.
Their "Naked Burritos" are AMAZING.
Qdoba is a lifesaver. I think I end up there at least once a week when I'm out of the house for 13 hours and am too disorganized to bring any food with me. If only I could remember to keep gluten-free soy sauce with me, I could mix it up with some sushi!