There was a recall on the radiator cap, as well as the upper radiator hoses,
you might want to check those parts to see if they are the updated versions.
Did you see actual signs of coolant leak? Like coolant residue somewhere in the engine bay, or on the ground? How much was lost??
If you have not seen evidence of a leak...Sometimes...just a possibility,
when they replaced the coolant when replacing the radiator, coolant could have spilled on parts in the engine area, and when it gets hot, the smell can linger on for a while. Also...if the cooling system was not bleeded correctly at the time of the replacement, sometimes, you could have some air finally out of the system, and so cause a drop in your coolant level, which might appear as a loss.
I would suggest if you see no signs of a leak, to top the level up and keep a watchful eye on it.
