Whoa, back up the train. She's married. Politely run away, don't walk.
I'd tell her if I were her husband, I'd be troubled by my wife taking/going with another man to a movie, so you don't feel comfortable with this.
Now if she wants to go as part of a work/class/whatever group, that would be fine. But this looks too much like a date for my comfort level.
Besides, hubby might be a homicidal jealous lunatic, and you are not a trained killer just yet
TB