this is called an “exponential back-off”: every time you enter a wrong pin, it takes twice as long to verify the next attempt. If you do it wrong again, it will be 4 minutes, then 8, etc., until at the 16th bad try the Trezor erases itself.
We haven’t seen any proven cases, but in the abstract it’s possible that something gets corrupted and your PIN is no longer recognised.
(it’s also possible that you are misremembering the PIN. human brains also have glitches. dunno which is more likely)
In any case, if you have your seed backed up, this is nothing to worry about: you can factory-reset your Trezor, recover from backup, and set the PIN again.