I think this book may have had something spilled on it, however the pages arent wavy or brittle. I just want another opinion before I mark that this book was received with problems, especially since its a wish list book! Thanks!

Looks liquid stained to me.

thank you :) This is only the second time ever I've had a problems with the books i've received, the first one was extremely obvious!

Pic #3 just looks like normal  tannen/age discoloration. 

Pic number #2 looks suspiciously like liquid damage.  Peek inside the cover on that side, and look at it in natural sunlight...even if it was plain water, the watermark will be visible.  This is the only time I take incoming books outside for inspection, if I see other indications of water damage...that always clarifies the matter for me.

Pic #1, is that the opposite end of the book from #2?  If the discoloration goes all the way through, then liquid damage should be visible on the pages...wavy or not.

It's also possible this is a stain, unpostable if it's too deep in the pages to be sanded off.  Say a reader picked up the book after a fresh application of hand lotion, then the oils darkened over time.

The first picture to me, looks like the book might have been sitting on a shelf partly in the sun. Books get a "tan" pretty fast, and if it is partially in the sun and maybe partially covered, or in a part shadow cast by something on the shelf, it can get marks like that.

The second pic looks more like some type of liquid, maybe.

The third pic, where the stain or whatever it is goes inot the pages, that maybe could be liquid too.

It's hard to say for sure, but I would lean towards liquid based on the 2nd and 3rd pics. Not the first, necessarily.

Good advice above.  I often rely on texture.  If the pages are stiffer where the stain is, it's liquid damage.  Hard for us to tell without touching the book.

I agree about the tanning.  Pic 2 is the only one that looks somewhat questionable, but usually the texture of the page changes if it's been wet.

I once had a stack of books in front of a window, and a few of them ended up with stripes--they had tanned from the sun coming in through the blinds.  Now, I'm much more careful of leaving books in front of windows for long periods of time.

Thanks everyone for your input :). This was a tough one!