The first thought that comes to mind if you are geocoding loans when not required to do so, or you are not using it for a defined self analysis or for CRA purposes (if applicable), are you redlining?
Off the top of my head I know of no regulatory prohibition from doing geocoding, but I've been geocoding since 1991 because of HMDA, so, I've never had any reason to look for such a regulatory cite.
_________________________
The opinions expressed are mine and they are not to be taken as legal advice.