If it was that often I'd tap on his shoulder and politely say " Hey, don't mean to bother you, but your phone constantly glowing in the dark is really distracting to me and my companion. If it's an emergecy I understand but if not can you please keep it off"
There's no need to be a dick about it
If that person still continues to do it, well nothing much you can do about it since you already asked him to stop
