TMP451-Q1: "ALERT" function is need to be calibrated?

Hi TI FAE,

Regarding the "ALERT" function. The action is base on "status register (0x2, bit [2:6])".
I did a test and put the DUT into the -40C chamber, and found TMP451 ALERT pull-low after booting
To read the register 0x2 = 0xA8 = 1010 1000 = local/remote low temperature limit

but our temperature low limit setting as below,
reg 0x6 => 0x13 = Local temperature low limit = -45C
reg 0x8 => 0x9 = Remote temperature low limit = -55C

The ambient temperature is only -40C, we read that the TMP451 is only -39C, it does not touch the lower limit.
so "ALERT" function is need to be calibrated? (or temperature limit )

Thank you.