I had aftermarket tints fitted to mine by a reputable company. The effect you are describing is caused by light TIRing (Total Internal Reflection) off the film which is covering the elements. because the elements are slightly raised the film can not sit flush up against the glass. It does it off the top and bottom edges. I suspect the top edge reflects light down the window and the bottom edge up the window. Not a lot you can do about it really. I've got used to it and don't really notice it now.
Current: 2013 F30 320D M Sport AW, 403M 19", Bi-Xenon, Black Leather
2005 E91 320D M sport, BSM, Twist 230 19's, Lemon Leather. Death by Swirl Flap
2002 E46 320i M Sport, Convertible, Titanuim Silver, 19's, Xenon, Black Nappa Leather
1998 Lotus Elise 111S, Black