rebuildfstab going to background

I have been checking a fews things on the pcmanfm 0.97 and udev and mounting removable media and so on, and finally I noticed that in /etc/udev/knoppix-post.rules is running /usr/sbin/rebuildfstab in background, ie at the back of the command, there is a '&'.

I am not sure of the original intent of that, but since rebuildfstab can be a slow process, it can happen that when pcmanfm is displaying the plugged in usb drive, the directory /media/sdb1 is not created yet but the /etc/fstab is built already ( ??? - that seems to be the case on my computer ). When user click on the drive, they get 'directory not found' thing. But if you wait long enough, the directory /media/sdb1 is created.

My system is not representative of all other systems, as I have already obsoleted 'hal' and already using pcmanfm 2 but nevertheless I notice more consistent behaviour after I remove the '&' and the end of the knoppix-post.rules.

Anyone what to share some observation of this on his computer ?