Ive heard the same thing, and for the most part I believe it. If you think about it, it makes sense; we humans are quite sensitive to over-exposure to UV radiation, so its logical for most window glass to be made to filter UV.
I don't know what plants you have and nor am I any form of botanist, but I'm going to go out on a limb and say that some plants probably do not require as much UV as many reptiles do. They mostly just need bright, visible light.
On a similar note, snappers really do not require as much UV as most other turtles, as they do not bask on a regular basis. So in your case, it probably doesn't matter much either way.
I suppose I'll take your word for it not "getting too hot" but I would implore you to make sure you're using a thermometer before you make such claims. Remember that reptiles are cold-blooded critters and their bodies react differently to certain temps. Whats cool for us, may indeed be too warm for them.