This temperature could possibly be a bad connection of the sensor cable to the board, as well as a possible condesation on the sensor's leads.

The sensor's leads are in heatshrink, then dipped into hot glue, and then again heatshrink. The only possible place that candesation can cause a problem is bettween the sensor's case and the hot glue. You can warm the hot glue with a lighter in order to seal again any cracks.

I did not use heat shrink on the sensor's surface because that would make it slower to respond to temperature changes, and bigger to the size.

Also there is no need to recalibrate the sensor, This is not a calibration error.

Cheers
John