Port 13139 - attack?

I am getting a whole series of probes on port 13139 all of a sudden in my firewall log. This started out of the blue about 6 days ago. There will be a string of them coming from a multitude of different IP addresses within a matter of seconds (I would imagine spoofing of the IPs from nmap or a similar tool). Of course the SuSE firewall2 is dropping all of them, but they continue. Has anyone else seen this happen recently. Is there a new attack of some sort which is directed to port 13139? I have never noticed this specific port before with so many hits and now it is starting to rival the old nimba entries in my logs. Thanks, Jim