Unwanted alarm

Hello

This morning : wake up, turn on the phone, unlock encryption, then alarm / stolen-lost state…

I was not sleeping anymore at this moment, sure !
But not really funny.

What could lead to this ?
Sim card physical trouble / not correctly connected ?
Minute after, I was able to finally enter pin code so alarm stopped…

PS : also had to enter anti theft pin after Sim pin to stop alarm

Any idea ?
Thanks

That would be my first guess.