Okay, so probably 2 months ago, I topped of my radiator and filled my coolant tank with 50/50 mix. About two weeks ago, I noticed the tank was empty when i was changing my oil. I went to a local parts store, bought a gallon of 50/50 mix and poured it in. I've been checking it every few days and the level seems to go down, I'm sure by next oil change it will be dry. Should this be happening? The truck runs fine and doesnt smoke like It is burning coolant so I don't know.
Thanks

 

You will have some evaporation but not that fast.
Chances are the system was low and has now replenished itself.
Just keep an eye on it for now.