The problem is probably the UHU glue having not had the time to cure through and interacting with either the PLA, the moisture in the garage, or the brick-paper's covering foil. Many of the metal-tube UHU glues - like "UHU Hart" - are resin-based and contain solvents that can interact with some polymers like the coating of the brick paper. Curing times can be up to 48 hours to cure.
I have had a very good experience with very basic water-resistant Wood Glue to both smooth over 3D-prints as well as attach layers of wood or paper to it. Most wood glues are made with a chemical that is the same or similar enough to those in Gluestick (usually PVA, sometimes PVP). These usually don't react with the fibers and surface of the NOCH-brand brick paper I know.
After having the glue dry thoroughly - for Express type wood glues that is about 2 hours - there is little to no chance that the two interact badly in the garage.