Why does the Star Note Lookup say my note was printed in Washington D.C. when the Federal Reserve Bank seal clearly says differently?

The Federal Reserve Bank and printing facility are not the same. There are two facilities that print US currency – Fort Worth and Washington D.C. Notes are printed only at those two locations, but then distributed to the 12 Federal Reserve Banks for circulation.

What currency reference books do you recommend?

If your interest in currency is limited to Small Size notes (series 1928 to present), I recommend The Standard Guide To Small-Size US Paper Money 1928 To Date.
If you also need information about pre-1928 paper money (Large Size notes, Fractionals, Confederate currency, National Banknotes, etc.) consider these:

For more information, see the reference book comparison page.

Where should I sell my notes?

ebay is a popular place to buy and sell currency.  Watch out for the fees, though.  Selling a $100 bill for $115 can cost you money after fees + shipping costs.

Should I hold onto this note?

What notes you collect, sell, deposit, or spend is up to you.  If you find a certain type of note interesting, collect it.  There is no rule saying that notes must be rare or valuable to be collected.  I have many notes in my collection that I like that will be worth face value now and forever.  Do you want to hold onto a note so it appreciates in value?  Okay, then do some research, get a reference book or two, and decide for yourself.

What is my note worth?

I don't know!  There are many factors that go into determining a note's value.  Each note is unique and takes time and effort to appraise.  I wrote a whole article about how to determine your note's value.  Enjoy!