I have a 12x36x1 return grill. I have a 3 ton pkg unit. I just noticed that my Boair filter is sized 11 1/4 x 35 1/4 x1. I had about a 1/4 inch space around filter that was pulling air into return duct. I put a 1/4 inch high density foam weatherstrip around my filter to make a better seal. Good idea?