ABC News offered its affiliates a special report at 3pmET/2pmCT this afternoon with the news President Obama endorsed gay marriage in an interview with “Good Morning America” anchor Robin Roberts.

ABC has eight O&Os that often promote ABC’s big exclusives. Five of the stations — WABC in New York, WLS in Chicago, WPVI in Philadelphia, KTRK in Houston and WTVD in Raleigh-Durham — aired the report with no special programming on either side, returning to “General Hospital” at its conclusion.

Interestingly, the three West Coast stations — KABC in Los Angeles, KGO in San Francisco and KFSN in Fresno — also did not promote the news on air, despite the fact that each has an 11amPT newscast that preceded the special report. (KABC’s newscast is an hour long, while KGO’s and KFSN’s are only 30 minutes.) All three stations aired a report from ABC’s Karen Travers on North Carolina residents voting to ban gay marriage on their respective newscasts.

One explanation for this could be the desire to keep the interview’s news secret until the special report aired.  As TVNewser notes, ABC News did a remarkable job keeping the news under wraps. ABC news staffers were told not to tweet until after the news broke, and no video clips from the interview were posted online until shortly before the special report aired.