Coolant smell after driving your Subaru?

Sometimes after driving my Subaru I could detect a coolant smell coming from around the engine area. It was more noticeable in the summer when it was warm out. I was keeping an eye on the coolant level and eventually it did go down enough that I needed to add some. I was never able to find anything or exactly where the smell was coming from. I was wondering if maybe it was just the smell of the coolant going back into the reservoir when the engine was warm, but the smell did not seem to be coming from the reservoir area. I never saw a leak or puddle or appearance of overflow.

My Subaru is a 2015 Impreza with a 2.0L engine.

Anyways I have had it in to be looked at a couple times by Subaru under warranty and they did find something each time. Once they had found a slight seep from EGR cooler and replaced it, then another time they found some coolant seeping by the coolant hose for the transmission cooler by the crossover pipe. I have not noticed the smell as much lately ( it has been colder out), but when I was just changing my oil, I noticed it was a little low again. So I filled it back up to the middle of the low and high marks while cold.

Subaru Impreza coolant reservoir.

Does anyone else have this issue? I have no other problems, but it just seems odd to be topping off the coolant every 4-6 months. Even though its not much. My other cars never need this done.  The jug of coolant should last me many years, but I still wonder where its going.

This is my first Subaru and if you have any insight on it please let me know.  I have googled and found others with the same issue on a few different Subaru models. But did not find anything definitive.

Thanks