Prefix Question

I got a $5.00 bill today with the prefix HNS. The type font of the HNS is smaller than that of the serial numbers. I compared this to other $5.00 bills I have and found that the other prefixes are the same font size as the serial numbers. My question is, is this common that the font size is different for the prefix or is it a printing error? For example the prefix HNS is font size 9 and the serial number is font size 10.

I have sometimes encountered the same thing. I don't remember what prefixes or what denomination of bills.