Being stuck to the glass may or may not have anything to do with Katrina. These prints (Including Niemann, Simbari and Luongo) were so heavy with pigment that they would often take years to dry properly. Any contact with the glazing would result in adhesion. I have worked with 2 of these (none lately though) and the only successful way of getting the pigment to release from the glazing was to super chill the glazing with dry ice. I would not recommend trying this yourself.
Most traditional paper conservators won't mess with contemporary serigraphy. Make sure in your search on the AIC web site you specify the age and technique used in printing.
One place you might contact is:
Etherington Conservation Center
7609 Business Park Drive
Greensboro, NC 27409
336-665-1317