I'm pretty sure it is, but just wanted to double check before sending.  Along the top of the pages (with the book closed) there is a stamp that just repeats "10", I'm thinking it's some kind of remainder mark so that should be ok.  On the back cover: the top outside corner is torn off.  I measured it and it's 1/2 inch long and 1/2 inch wide.  I know some used book stores cut off the corner and it's ok as long as it's under 1 square inch, but does it matter that it is ripped off instead of cut?

Like I said, I'm pretty sure it's ok, but I've never had a RWAP and don't want to start so figured I'd ask you all.

Thanks in advance!

Yup--sounds postable to me.

The stamp is definitely okay. 

Here's the rule on the corner:

"some used book stores cut out a small part of the cover; if the amount missing is less than 1 square inch, this is OKAY", so 1/2 by 1/2 is well under the limit -- if it's triangular, being a corner, that would make it about 1/8 square inch. (.5 x .5, divided in half since the triangle is half of a square.)

If you can trim the tear with scissors, and still have it under 1 square inch, you might consider doing that.