Found it, thanks to the guy that posted the site with the legal interpretations.

https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/Data/interps/2014/Yu-Southwest%20Airlines%20Pilots%20Assoc%20-%20(2014)%20Legal%20Interpretation.pdf

It says it all right there about "automatic extensions." I was talking to my CA during my trip here at PSA, and it is a common belief that extensions are automatic here. Absolutely not true and here's the document that says as much. Spread the good word.