Yes, you are the only one, because you've misunderstood.
> Most bugs don't come with their own updated alert text. It sounds a bit more like they had planned to switch to a different trial method and enabled it earlier than they expected?
No, the bug was simply that the trial period ended after 15 minutes instead of the intended 15 days.
> Or maybe a "rogue" employee added the feature as an experiment and didn't tell anybody?
There were no employees. At the time this happened, the company consisted entirely of the 3 cofounders. In fact the bug, that is, the shortened trial period, is what allowed the company to grow and hire employees, although the company is still relatively small.