Meditation thought fragments

I've been meditating a fair amount lately, and the weird thing is that when my mind gets very quiet something like a thought or a voice occasionally jumps out. Yesterday a sentence jumped into my mind, and I thought "What the heck was that?"

It wasn't a sentence that belonged in my head, it was like a thought for someone else. I don't remember the sentence exactly, because I was trying to clear my mind and let things like that come and go, but it was something like "Call Bob in the morning" ... but I don't know anyone named Bob.