At 16k miles my engine coolant was pretty damn low. Is this normal?

 

Depends, where you live? If it's in a hot geographic area, then yes, it could be normal as the excess boils off on the vent tubes...if not then I'd say worth looking into. Just my thoughts reading your post...

 

how low is low? just tank low?

if rad low, not norm for a car 1-2yrs old. start by checking your rad cap. look for torn rubber seal.

i'm guessing that you filled up your tank. keep an eye on the level. check everyday for about a week, when cold is the simplest. use a marker to mark the level and check at the same time. if you notice a loss in a weeks time take it to the dealer and have them find and fix the fault. good luck.