Strong Antifreeze Odor

I own a 2002 2.4l 4 cyl Galant. Lately, I smell a strong Antifreeze odor when I shut the engine off. I don't see any Antifreeze leaking under the car. I recently had to add some Antifreeze to the overflow reservoir. The car has 98,000 miles and I am the original owner. The car has never ran hot or overheated.

Do you think its a blown head gasket?