Gliding Shadows

I had a very strange experience last night. I crossed the house about 11 pm in order to speak to my son. As I headed back to my room, on the opposite side of the house, I saw a dark shadow, about 4 1/2 feet tall, gliding swiftly in a northwesterly direction, from the study toward the family room. I turned to the right in surprise, following the swift movement of this shadow, only to turn just as it was passing in front of me, also in a northwesterly direction. In fact, we made contact of some sort, which felt a great deal like opposite magnetic poles - I felt myself physically pushed backward.

My first thought was of another son who lives in a nearby town. I called him immediately, and just said "Be careful, and pay attention to what is going on around you..."

The shadow was vaguely human shaped in that it had a rounded top about head size and a large extended area below that swept the ground. It was nearly opaque, but not quite. It glided noiselessly, and, apparently, was able to quickly redirect... Unless there was more than one?

I have unexpected experiences with afterlife spirits since I was a young child, and some, in my adult life that left me quite emotional and shaken. This was a completely new kind of experience, but after my call, I went right to sleep, and was just fine. Quite calm, actually.

It leaves me shaking my head, though. Any thoughts about what this might have been?