Is this Legal?

There I was, drinking my tea this morning, getting ready to go to work. I was up a bit earlier than usual, so there was time to get onto one of the chess servers for a quick game. I didn't realise just how quick... but of course one can never know this. My opponent was a Russian chap. His rating wasn't high, but respectable. A five-minute game, and I am Black:

1.e4 d5 2.exd5 Nf6 3.c4 c6 4.dxc6
If you are going to take this pawn, you have to know what you are doing.
4...Nxc6 5.d3 e5 6.Bg5
To the cognoscenti, the first sign that White is drifting.
6...Bc5 7.Nc3
Intuition is a funny thing. Here I knew my invisible opponent wanted to gang up on my pinned knight, so I made a move that helped his knight find the "right" square for this project.
7...Be6!?
No points, by the way, for 7...Bxf2+? 8.Kxf2 Ng4+ and now 9.Qxg4! leaves White a piece ahead when all the captures are over.
8.Ne4?
Taking on f6 and then playing 9.Ne4 doesn't help White after 9...Bb4+ 10.Nc3 Rd8 with unpleasant pressure (or pleasant pressure, depending on your perspective.)
8...Nxe4!
Again, no points for other moves.
9.Bxd8 Bxf2+ 10.Ke2 Nd4 mate.

Yes, I know: it's just Legal's mate with reversed colours. Nothing too special... except that I could not find a single previous example of this in any of the big databases!