Topic Mogu Architecture and The Light
That's very clearly the symbol used by the Church of the Holy Light that can be seen all over the place in the game, from the Archbishop's pope hat to wooden not-quite crosses at graves and SM.
Very obvious Light symbol is an obvious Light symbol.
And as for reuse, that door looks like it was designed for its current surroundings and I don't ever recall seeing any other quite like it.
You may have found something of note.
Edited by Mordstreich on 10/9/12 9:04 AM (PDT)
We see the symbol wherever Humans and the Light is given significance. Scarlet monastery, grave markers, etc. However consider this:
Humans came from the Vrykul, who used to worship Titans. When the Humans found their new world after being evacuated from Northrend as the curse of flesh began to mutate them further, they were still naming things after Titanic origin long after they stopped worshiping them.
It's been speculated (I'm not sure if confirmed) that the Mogu and the August Celestials are Titan creations.
So it's incredibly likely that symbol is Titanic in origin and that gate was built by them or their workers.
Actually Stormpike's Battle Standard look like the Ironforge banner - A warhammer under a circle with the silhouette mountain inscribed. Similar, but not equal.