Well, it may just have something to do with their monster win at Newcastle at the weekend. Actually, let me change that, it has everything to do with that win.
For a long time, it looked like it was going to be another afternoon of pain for the Gunners at a ground that has inflicted so much damage on their title hopes in the last few years.
But this new and improved version of Arsenal did not give up, and they turned the game on its head late on. Mikel Merino levelled things up with five minutes to go, before Gabriel won it in stoppage time.