Terribly unfortunate for you. Any answer other than "we'll send you a new one for no cost" will be painful, but a broken screen is not considered a defect until which time either the manufacturer determines there was a defective manufacturing process, or until a class-action suit is brought against a manufacturer and as part of the settlement the manufacturer either agrees to or is ordered by the court to resolve the defect. You have heard of "recalls". This would be the likely scenario to resolve this problem, if it's widespread and in excess of the norm.
As for the new phone being likely to crack as well, I have a thoery that goes like this. The extremely thin phone becomes more subject to flex on many angles and several axis, but in an attempt to alleviate that, the manufacturer decided to create a "lamination" effect by fusing the individual layers together into one quasi-unit - not too unlike Plywood. This is done with double-sided adhesive between selected layers. Then there was a Stainless Steel "frame" or backbone (a rectangular box) which runs the circumfrence of the phone internally and was intended to further "stiffen" the phone. Still unfortunately the multiple efforts to strengthen the phone and reduce flex may not have been enough to offset the ultra-thin glass on both the digitizer and the actual display which is fused to the digitizer, so in some cases one will crack but not the other. It also seems that in many cases even large falls from great height (top of a ladder) have little ill effect whereas unfortunately even small falls like yours, or dropping something on it (a bracelet from 6") results in cracked glass. I think this ill effect from relatively minor bumps is due to the glass already being "stressed" by possibly the lamination and/or the bezel (metal surround) placing undue pressures on the two glass components.
So the short answer (yeah, I'm long-winded), is that you may have no problems with your new phone, or you may have another unfortunate event similar to this. What I would suggest is to add an Otterbox (either the Commuter or the full case), and you may reduce or eliminate the causes of future damage.
