[CentOS] odd automount issue

We're seeing, in the log, automount trying (and failing) to mount a few
directories NFS in the middle of the night. For example:
03:49:50 <my own workstation> automount[7872]: key "httpd" not found in
map source(s)

It doesn't seem to be triggered by the pen testers, nor by logs (I think),
so we're all at a loss to guess what's triggering this. Anyone have any
thoughts on it? Most of our systems are 6.5, btw.

       mark