Over the past week, I have noticed a strange smell coming from under my 2009 Acura MDX after driving. I looked underneath and found nothing unusual or anything leaking. The smell is similar to Round-up (I know, thats weird). In fact, I first noticed when I pulled into my driveway and thought my wife had sprayed Round-up. Its also similar to burnt popcorn, but not nearly as intense. It dissipates after 2 or 3 minutes. There is nothing stuck underneath, like a plastic bag stuck to the muffler and none of the calipers are stuck. I checked under the hood and it is not coming from the engine bay either. Anybody have any idea what this might be?