I'm going to add my 2cents but I'll start by saying I'm by no means a mechanic. On the other hand I'd also like to think I'm not a total idiot either.
Something doesn't add up to me. First you say the oil was low but above the fill line. 'Low oil' doesn't mean 'no oil'. Not to mention the light didn't come on. Yes lights can fail and you shouldn't rely on it but you also had the oil changed not that long ago.
The issue to me is 'did the engine fail because it had no oil' or 'did it have no oil because the engine was failing'. With the information you've given, low oil, recent service, I'd speculate that the engine had a problem first. I'd push a little harder for warranty on this.
