I have never had to disagree with Yorgi and same this time!
CPO (or any other warranty) is for the provider to make money... thats the bottom line, else they won't be offering it.
With that being said, if you do all the maintenance yourself and with a little bit of good luck, you will do well without the CPO.
Of course there are cases where you have a major repair and the CPO will come in handy... (same goes for home fire insurance, flood insurance...)
Back to the OP's question, at 22k miles, you really should not have much to worry about (again, don't come beat me up if you had to unfortunately have a bill repair bill...lol)