I wonder if there is any significance to those numbers? Is it the birthday of whoever minted them or something?

It looks like they were just generated (or stored) as 8-bit integers instead of the intended range.

(While the smallest one being 4 memeworthy, I don't see any particular indication that it's exceptional within the samples, rather than just the smallest when sorted. So they're probably all 8-bit keys, not 3-bit—it's the (unknowable) generator distribution, not the width of the actual key).