Burning Smell - ???

I have a 35d with around 1000 miles on it. Several times (but not every time) when I drive into the garage and get out I smell a burning smell around the car. It's hard to isolate it, but it is not evident inside the car, and not really from the engine compartment either. It is not the brakes, as they were quite cool the last time it happened. Anyone have any ideas? Is it just some coating on an exhaust burning off maybe?

Thanks in advance for any help.