I'm having the same problem and it's always just one wheel, not multiple wheels and not a total lockup. Twice the caliper got really hot while I was going down the highway at speed, hitting the brakes rather lightly only to exit to a rest area. The other times were during solo driving with no heavy demands on the brakes.
My suspicion now is that the brakes are dragging not as a result of normal use. In other words, I began to suspect that the ABS unit was somehow involved, reasoning that if I'm not riding the brake, then the only other normal way that brakes would be applied is through the ABS system. I too had also heard that the brake hoses could be the culprit and mine are original. But recently I just had the ABS sensor throw a code that it was bad and have replaced it. So far so good but it's too early to tell.
But I am still planning to replace the hoses and maybe the lines with stainless braided before the season begins but I'm trying to first satisfy my curiosity on if it was the ABS sensor on the pumpkin.