I guess you've discovered since you fixed it? I stood inside the woolly doorway and typed "/setwarp pool", but then actually warping there was sending me into a small underground cave somewhere below.
On a related subject, my reason for doing it in the doorway was to make sure it stayed safe - when I first went to /home to get out, I was suffocated - presumably wherever I had my home set to was built over or something - and I've noticed the same thing has happened to warps before, so I was wondering: are there any bukkit plugins that can check to make sure the warps are still valid, and either fix or block ones that end up underground?