Hmm. Was the water bath at temperature before you started timing? 160F is the start of when the whites will be fully formed. Looking at the guide over on SeriousEats, I think I'd be more tempted to cook them at 165F:
Me, I tend to make deviled eggs a lot, so, I'd be tempted to increase the time a little bit too - with hard boiled, you're really not looking at having any of it "soft". An extra 10 minutes could make a difference if you have an extremely cold fridge (i.e. colder starting temperature for your eggs).