Improving my SSHFS script

I can name more than a dozen machines whose file systems I would want to mount from work. I don't mount those file systems all the time, but I do often enough that I have a Perl script I use to manage my SSHFS mounting and unmounting of them.

Here's a problem. This weekend, the servers for work were taken down for scheduled maintenance. That's fine, but it does mean that I had to remount a bunch of them this AM, and when the script went through the already-mounted filesystems, it would ask for a password and say "this is already mounted". What I probably want is some way of knowing quickly whether there's something mounted and then doing that check before I do the mount.

And this is what initially draws my attention: mount points are directories. And directories can contain files. It is a known trick for hackers to unmount shares, hide files in the mount point, and remount, where sysadmins won't notice it. It strikes me that I can touch a file like .unmounted into each mount point, and then look for that file on each remounting, and skip it if I can't -f that file.

But really, this has to be a solved problem somehow, so there might be a better way. Pointers?

ETA: The code, a few revisions back, is part of a previous post. A twitter response is leading me to start the process of finally using my github account and setting it up there. Will add again when I get to there.