If the film was from dissolved stationary phase material, you would see a significant distortion in peak shape for all your analytes due to the void that would be developing in the column. If it was from the stationary phase being hydrolyzed, you would see a change in retention and/or peak shape for your compounds.

Be sure that you are operating within the specifications of the HPLC column. It is in fact possible to dissolve the packing material or hydrolyze the bonded phase if the column is used Improperly.