Q: If there is a "changed circumstance," when does the loan originator issue a new GFE?

A: When there is a "changed circumstance" and the loan originator intends to issue a revised GFE, the loan originator must do so within three business days of receiving the information sufficient to establish changed circumstances. A loan originator may issue a revised GFE reflecting only the increased charges resulting from the "changed circumstance".

This can be found in GFE-Changed Circumstances – FAQ #3 of HUD’s FAQs.  HUD’s FAQs can be found at http://www.hud.gov/offices/hsg/rmra/res/respa_hm.cfm.