Does my mom require a new travel visa?

Friends, Here is the situation we are faced with. Need your advise in this matter.

My mom visited me in the states last year june and she was eligible to stay here until Dec 6 2009 as per her I-94.

We applied for her extension as the situation at home demanded her to continue her stay. The decision of her extension (snail mail) did not reach us until Dec 6th. So she continued staying here. When we looked up the website for the decision of extension accidentally since her I-94 expiry date was nearing, we found that USCIS had declined her extension on Dec 3rd.

We requested USCIS to mail us the decision and it reached us on Jan 1st week after multiple follow ups. Meanwhile we tried to get a company for my mom's travel and she left the country on Dec 28th. So, in effect, technically she overstayed for 22 days but because of not knowing the 'decline' decision for her extension.

Now, the question is, is her visa invalidated because of this overstay? Would we have to apply a fresh visa for her? She needs to be here during oct because of the personal situation at home.

Pls help!