not at all bizzare.. he commited a super chess sin not only did he allow you to get a discovered check but after he was in Check he moved his king instead of developing Bishop.
Great Job
After Be7 Dxe7 Qxe7 Qxe7+ Kxe7 You have Multiple pieces to move that will leave u with a CRUSHING advantage.. not to mention the black king cant castle and is in the Open.
The reason I'm posting this is because I didn't really have to move any of my pieces after their development for the mate, making it an oddity.