This is a late response but my father passed a few weeks ago and also experienced this. It was the moment I knew he was gone without even knowing about lacrim mortis. He wasn’t seemingly breathing and had no pulse on the pulse ox before the tears but I am hoping he was still with us until the tear point bc even though he was comatose I said everything I needed to say. I hope he had a pulse and it just didn’t register. I wouldn’t forgive myself if he passed while I was asleep. I should have stayed up all night with him knowing how bad he was but I was just so tired.