No that doesn’t really make any sense. Did you run an apt-get update or anything? I know that if a new kernel shows up it will most likely overwrite this one. I haven’t run an update since I installed, and have had my PI on and off since. Possibly even there being a two week stretch without it on. But can’t say for sure.
Definitely odd if you didn’t update, because I don’t think there is an auto update.