The original tokens still show up as valid when used with /account/verify_credentials or other API calls.
I have not tried requesting new tokens through OAuth. I am using these tokens to document single-user OAuth, so they were created using the dev.twitter.com UI.
The consumer key for this app is m6oeHBbFqUk3gvfVbnjiw.
The access tokens were created with an earlier consumer key. When I couldn’t change the access tokens, I reset the consumer key and secret through the dev.twitter.com UI. These values changed, but the access tokens did not. I am now testing with the new consumer key and secret. These work with the original access token and secret. I feel pretty confident that my test code is correct, since changing any of these tokens in the code causes verify_credentials to return a 401.