Looking at White House photos on Flicker, and zooming in on POTUS's tie, analysis indicates that the photo Daniel Scavino Jr. posted to [FB] on Dec 15th was taken on Mar 11th. That's 3.11; which mirrored is 11.3.
"Historical moment in the Oval—will share what it was, one of these days, when I can…."
https://www.facebook.com/DanScavino/posts/2779175482298170