Aeropostale Childrens Clothing Store Name Selection

Aeropostale, Inc., a mall-based specialty retailer of casual and active apparel for young women and men announced June 18th, 2009 that it has opened its first "P.S. from Aeropostale" store in the Palisades Mall in West Nyack, New York. The Company plans to open approximately nine additional stores, primarily in the New York metropolitan area, during fiscal 2009, as well as an e-commerce site at http://www.ps4u.com.

Where did they come up with the name "P.S from Aeropostale". Is this like "post script" when authoring a letter. Meaning an "after thought" or something that was not relly planned but at the end, they thought it might be a good idea.

I am sure that their is a meaning to the "P.S" for Aeropostale? I just do not yet know what it is? Do you? If you know the correct meaning of "P.S" in this case, please let me know in the comment section below.