There is no minimum/maximum age requirement for making friends. Making friends is a human need that transcends age, race, ethnicity, gender, geography, or political boundaries.
But, in order to make a friend there needs to be a connection, a contact that is lasting and meaningful. This staredown was very intense for several seconds, but separation by a single glass pane prevented any meaningful connection to be made.
In this case, the bond had already been made earlier, the glass was just a temporary separation. The earlier, physical connection, is what makes this a lasting friendship.
Thought for the Day: No symphony orchestra ever played music like a two year old girl laughing with a puppy. Bern Williams