I've been told that the "Sudden Increase in traffic to a port" means that MARS has seen a situation where the traffic to a port is more than 2 standard deviations from its normal traffic rate.
In the normal course of its operations, MARS develops a baseline of the network using Netflow. Consequently it's perfectly normal for there to be moments where you have spikes in traffic which would trigger this sort of event. It's then up to the administrator to determine if this is a false positive or not.
Hope this helps.