Today I had virtually no activity on the site (other than visiting) and to my surprise I somehow just earned all of my tag badges simultaneously. As far as I am aware I already had all these badges before, earned at the appropriate time but they are now showing up as earned today.
You can see the effect in my activity. I also got the corresponding notifications:
I honestly don't think this has much of an impact other than the momentary confusion caused but I am still curious as to what happened, and whether this is worth reporting to the main meta.