What Are the Odds I’d Get THESE Two One-Dollar Bills in Change at the Same Time?

I didn't notice it immediately. Who would? In fact, I almost spent them. And that's when I noticed something odd about these two one-dollar bills...

So, what do you think are the odds I'd get two one-dollar bills that began circulation in 2013 that have CONSECUTIVE serial numbers.

These two singles came off the press FOUR YEARS AGO and have been reunited!

On the other hand, is this more common than I realize?

On the OTHER other hand, though, how COULD it be?