Hi Ryan, this time of year I always blame the weather. By which I mean, warming temperatures are going to make your dough rise and ferment faster than it has when you made the same recipe earlier in the year, when your home was likely cooler. It sounds like your dough might have been slightly over-fermented. When dough over-ferments, the gluten structure starts to break down and isn't able to hold all those fermentation bubbles in place as effectively. This can result in the kind of large open air pockets you describe, along with flatter parts that don't rise well. One solution could be to use cooler water to mix the dough. Yes, the recipe says 80°F, but this needn't be written in stone if your home temperature is already quite warm. In some cases, using room temperature water or slightly cooler might be totally acceptable. Check out our Desired Dough Temperature blog post for tips on how to adjust your water temperature when your environmental temperatures start to heat up. On the other hand, because this dough dwells at room temperature for quite a long time, it will inevitably come to  room temperature sooner or later, no matter what temperature water you start with. So, the other solution is to keep an eye on your dough and not let it over-ferment. This will likely mean reducing the bulk fermentation time (in the bowl) to considerably less than 6-7 hours. Keep an eye on your dough and when it's tripled, it's time to move on to dividing and shaping. You could also consider refrigerating the dough for part of the bulk ferment, as PJ does. 

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