TSA isn't going to have a hangup over a typo on the middle initial. That being said, I'd call back and ask if they can check their Secure Flight field to see if the issue is there.
http://www.usairways.com/en-us/trave...ureflight.html
They should be able to fix it, but again, I don't think it's going to be a problem. For example, my reservations shows my name as "MykleBoBykle FiFyFoFykle" but my boarding pass doesn't print all of it....it shows "FiFyFoFykle/MykleBoB". It's never been an issue at all. Don't stress over it. You aren't the first travelers to have a slight misspelling on their name...and you won't be the last.

Edit: Just found this page on the TSA Web Site:
http://www.tsa.gov/what_we_do/layers/secureflight/
At the security checkpoint, TSA strives to ensure your identification and boarding pass are authentic and validate you are who you say you are. Small differences in the name on the boarding pass and ID, like middle initials, should not impact your travel. It is not uncommon for the information printed on boarding passes to differ slightly from the information on IDs, depending on the boarding pass printing practices of individual airlines.