I assume Iave DH too, noe diagnosis but I have this burnig itching rash on gluten. It came back when I baked bread for dh last fall so I gave it up. It is known that DH patients often get the rash back from airborne gluten. It is not recommenden for celiacs to work in a bakery or other places with foulr in the air...
I do not know about a short-time exposure to flour away from home.

nora