Musty carrots or thyme?

Made a soup this morning. When I was sauntering everything it had a funny smell. I thought I burnt the thyme with the onions I was sauteeing. But as I walk in - the soup has a funny dusty, mouldy smell. Simple soup - onion, garlic, thyme, salt, pepper. Carrots, white beans (canned), ham hocks. As I type this I'm wondering I it was the carrots. I noticed it when I only had onions, garlic, thyme and carrots in the skillet. Nothing was obviously bad. Anyway- does not smell right at all. Any ideas??