I've seen exactly the same thing and have assumed that this is down to the SEOMoz crawler not being able to pick up the settings in Webmaster Tools.
Have you noticed an improvement in your Webmaster tools reports?
I don't know if there is anything you can do at this stage, regardless of whether you're looking at SEOMoz or WMT. I wouldn't be too concerned about it if you have correctly set parameter handling and backed that up with some canonical tags if appropriate.
Very often, these alerts are meant to flag something for you to check with a human eye, but this and all of the above is my interpretation of what you are describing from my own experience so I guess you need to wait for A Mozzer to reply about the intricacies of what their crawler is telling you.
