I don’t recall anyone mentioning that it occurs after the calibration, but it isn’t the first time someone’s mentioned parts of the screen not responding - there’s more here:
Unless I missed something, the TL;DR version is: sometimes re-assembling the screen (detaching and then reattaching the screen module, that is) solves the issue, in some cases the screen needs to be replaced (usually under warranty; contact Fairphone support for that).