This isn't a problem, just a curiousity.

When I logged in I had a book that was on Wish List Hold from my bookshelf.  The odd thing is that this is a book I posted back in November.  What criterion is necessary for something to end up on Wish List Hold?

Someone may have had their account on hold with the book on their WL. When they re-opened their account the system processed the WL request against your book.

Or they were the only wisher and had that book on individual WL hold. 
 

I've had that happen to me before. I put my account on hold a lot to control postage costs. I'll take it off to post a WL book and then another book pops up on WL hold. One that wasn't WL when I posted it.