I have the book Dates From Hell-a paranormal romance anthology that is WL.  Some of the pages are wavy when you look at the side.  I bought this used.  When you look at the pages it looks like someone used one of those clip on page markers as you can see the indent.  I'm worried it might look like water damage to someone. There are no stains or anything.  Just these indents in the pages. 

As long as the book is readable, go ahead and post it.  You may however, want to give a heads up to the requestor before you send it, explaining the condition, so they won't think it is water damage when they get it.  They may however, change their mind about the book, but that is better than sending it and having it posted as received, but with a problem.