Maybe the phone was silent but still flashing a screen? Mine does that in that mode. At my first job we had a guy who could spot incidents coming on the monitoring dashboard before they happened. He never managed to explain or even understand what he was looking for and no-one else picked it up, but he would just see something that made him say things were odd, and most of the time we'd get an alert shortly after.
Maybe some signals just bypass the part of the brain which deals with well defined facts. I read somewhere about a construction foreman (HN comment maybe?) who gained the respect of the crew by having an unusually good hit rate in finding piping in the ground or walls. He started to believe in his superpowers but later came to the conclusion that he just subconsciously learned the typical patterns, plus an occasional non-obvious sign. Something like a vent pipe in the wall of the building telling you that sewer piping is probably below ground.