It's obvious from a short YouTube clip that Boxer was already fed up with this guy, Brigadier General Michael Walsh, probably because he's a.) in the military and b.) because he has something to do with the rebuilding efforts after Hurricane Katrina.
This incident is barely worth noting, other than as another example of a liberal elite reveling in her power--and striking an insincere pose as some kind of feminist. I have nothing but respect for female politicians (see my recent post on Nikki Haley of Bamberg, South Carolina), but this time Boxer has just made a spectacle of herself.
You can find the article here: "Boxer, the U.S. Senator, Chides Brigadier General for Calling Her 'Ma'am'"
Note: This post is being made a few hours after it was written due to Internet connection difficulties. Please let me know if you have any additional updates.