The Nose Knows ...?

Yesterday, when I was driving home, I drove through the tunnel down the road from my house, and it smelled like a cow pasture. All turdy and sweaty, like fresh-laid mulch, with a hint of wild onion.

Today, when I was driving home, I drove through the tunnel down the road from my house, and it smelled like an ice cream cone. Not the ice cream, just the cone. The plain kind.

I don't know what that means.