I have always come off as flippant and inappropriately flirtatious, or giggly, or smiley after a traumatic experience. I remember more than one therapist saying, “you DO understand that what happened to you isn’t funny, don’t you?”
But I dissociate very easily, and find remaining present to be almost impossible in the best of circumstances.
I have a good friend who does something similar to what you described, though.
Coping mechanisms are such strange tools.