That is very weird but not out of the ordinary. I've seen a few people that were approved the day after Biometrics.
Your record must have come back squeaky clean and super fast that they prob still had your file near the top of a pile lol.

Congrats man!

Edit: I was approved yesterday, my I-765 says card being produced while the Form I-821D says it is being processed. That happened last time for me too, usually gets updated within a day or so.