Even before the battery died it did seem weak. The starter motor always seemed to turn sluggishly when I keyed the ignition, like the battery wasn't able to deliver it a strong enough current. That made me suspicious either the battery wasn't able to hold enough of a charge anymore or the electrical system was failing to recharge it properly. Like Hawk said in her comment, we would've returned the vehicle after the jump to ask for a swap, but the depot was 2.5 hours away. We were not going to interrupt our trip any more than the 60-75 minutes we already lost.