Every CCP log you've signed assumes the thermometer was right. Where's the record that says so?
A CCP log is a claim about a reading. The calibration record is what makes the reading worth anything. 21 CFR 117.165(a)(1) requires calibration or accuracy checks on process monitoring instruments, 117.165(b)(1) requires the method and frequency in writing, and 117.190 requires the record. What a calibration log that survives a review looks like, sized for a two-person shift, and why a drifted probe with no record puts every batch since install in play.