Hey Kyiesdad,
What you have is called a "star" note.When the Bureau of engraving and printing pulls note that don't pass inspection,they replace them with new ones that have the same serial number,but replace one letter with a star.
It's some special law that says a serial # can't be used twice.Not sure of all the details,but I know they are somewhat rare.According to a 2008 price guide I have,your note has a value of at least $2.00 more than face value.As the current star notes in circulation today become worn out and retired,that value will only rise.
Star notes are very popular with collectors.
If you can afford to keep your note,it's a good investment.
Paleo10kbc