No Signature Required

Seth Roberts finds a store that doesn't use pennies.  He also discovered something else:

Here and there I have made small credit card purchases (< $20) with no signature required.

I made this same discovery at Borders the other day.  I bought a book with my credit card and the sales clerk simply handed me the receipt and wished me a nice day.  I asked if I had to sign anything and he said: "Not for purchases under $20."  That surprised me and I asked how long that had been going on.  Apparently for 1-1/2 months now. 

I didn't notice this before.  I'm not sure if it's because I hadn't been using my credit card or because my purchases have been over $20.  I'm guessing it was the latter...