Someone from Amazon keeps visiting my site

I have a site where I sell stuff from amazon. Clean, white hat, it is a site I take care of a lot.

I have noticed in my logs that 207-171-180-101.amazon.com seems to be visiting it frecuently, browsing around several posts.
Has anyone else noticed this IP in his logs? I just wonder why the heck are they checking out my site so frecuently.

They want to make sure you're being legitimate and not breaking their TOS. They want an excuse not to pay you if one is there.

Well, that's what I am worried about, since I have close to $1500 in pending comissions last month and I already have over $200 so far this month.

could also be some sort of crawler?