That's very interesting. Yours was definitely made before mine. So either the installation of 18 vs. 18x sensor is unrelated to the build order, or the older 18 sensor also will suffer the date problem but is just has no update to fix it.
Please ask Tesla to report back which version of the sensor is installed. Well, I guess if they are able to update the sensor that's already installed, we'd know it was an 18x. Or if it is an 18 they may tell you it needs to be replaced.
If Tesla says they aren't able to do the update, or if they want to charge $500 and you'd rather do the update yourself for that price, I can lend my cable to you after January 26.