My Dentist Just Gave Me a Take Home Tooth Whitening Kit That Has 35% Carbamide Peroxide in It. Teeth Turned BRIGHT White- Why?

Are you referring to your teeth or gums being bright white?  If it is your teeth, then congratulations on a successful whitening procedure.  If your gums are bright white some of the bleach leaked through the barrier during the whitening procedure and caused this.  Not to worry as this white appearance will subside in about 24 hours.  Hope this helps.  

Is it the TEETH that turned bright white or the GINGIVA (gum tissue) between the teeth?

 If it's the teeth, that's what Zoom & any other whitening product is supposed to do. If it's your gingiva that turned white, discontinue its use, show it to your dentist & perhaps the amount you are placing in the tray is excessive, or perhaps the tray is overlapping your gingiva too much. Your dentist will be able to quickly remedy the situation.