Well, it is going to happen sooner or later. It has happened to me, I might forget part of my lunch, or I may forget to grab my lunch bag entirely!
I would not fret too much over it. If you were only missing one carb block, it might still be adequate to keep you in the Zone. I think, in your case, I would eat lunch just the way you had it, and if you were to run into trouble, then eat the Pria bar later (not exactly balanced, but since I don't know your other choices, it might be the lesser of the other evils out there).
Have you considered ordering some Zone bars online? Just a suggestion. I try to keep an emergency supply. I don't eat them on a regular basis, but if I am in a pinch, I will use them.