Well, the most obvious theory to come from this information is that trying to be social made you think of how you present your face more, which made it appear in your dream.
Personally I tend to remember things and dream from a first person perspective. When awake I tend to whip up some arbitrary substitute character for my voice and appearance when I do go away from first person perspective. Seems less like I can't envision myself and more that I feel as though I shouldn't bother, that I should actually seek mutability in traits I don't see as really defining.
When dreaming, I usually do seem to have my own body, though I rarely out of my way to make sure. This is often sidestepped in a way by having the dream be of playing a video game, but at least one time I just outright started out with a sense of playing the role of a character and that I should just roll with not being me. But this was also that dream that acted all dumb and artsy.