Printer agent?

My mac pro (os x 10.6.8)  started to show this message every time I start up the computer:

'Do you want the application "printer agent" to accept incoming network connections?Clicking Deny may limit the application's behavior. This setting can be changed in the Firewall pane'

I checked the Firewall settings and it shows:

Printer Sharing : Allow incoming connections

There are bunch of printer agents, some with connections allowed and some denied (probably depends upon what I chose to close that message at start up)

There are three printers connected to my mac: Canon pro9000, Brother MFC 7860 and HP Laserjet p1102w. All are connected using usb. The Brother and HP printers have built in network cards to print from other computers at my home. I have been using these printers for long time without any problem till now.

I'll appreciate if you'll can help fixing the problem.

Thanks

Krishna