The most likely scenario is that someone bought a used sail from the person with sail # 1609... and then didn't race themselves, so saw no need to change the number. Possibly time for new sails by now - you'll better enjoy your boat, and you can ask the sailmaker to put the correct sail number on it!
(Now, if you join the Day Sailer Association (DSA), who, among other things pay for the site to host this forum, their secretary can indeed "assign" a number to you. They did that for me, although in my case it was just to make sure that what I thought the sail number should be, was actually associated with the boat. The DSA runs a membership site, where all the stuff other than the forum happens under
https://daysailer.org - note that despite the obviously related name, it's a completely different site with it's own username/password for sign in).
PS: if you'd like to discuss the merits of getting new sails even for a non-racer, the place to do that is the "Sails" section of this forum. I bought my first set of new sails several years before I discovered an interest in casual ("beer can") racing; so you don't have to be a "racer" to enjoy sails that set properly and still keep their shape.