Actually, this is a very common thing to do. Do you know of the “higher Self”?
What happened was that you most likely were in a relaxed state of mind, and able to access parts of your mind that you normally wouldn’t access. You were able to “see” into the mirror and actually see yourself, for yourself. Your Higher Self was most likely trying to show you something that you are able to do, but have rejected as too far ahead of you right now, or maybe, you see yourself as too young, weak, etc., to do a certain thing. This would only serve to tell you to go ahead and unlock that door. You’re capable of doing whatever this new task is, and so much more.
Is this scrying? Yes, sort of. This technique is used a lot in witchcraft circles, and I have heard it said that it has no place in the Jedi community. BAH! This is an opening to something greater for you. Embrace it!