Pizza dough dipping in middle during proofing
In general you should be fine, I would give this dough more time to warm/"re-proof" on the counter before shaping/ baking. 

I've seen something similar in other doughs, but I don't know what caused it. I don't expect much proofing in the fridge, and I've seen some weird stages when I try to slow a proof in the fridge (start a dough then finish it the next morning.)

If I was forced to guess.. 


This dough may have been handled more roughly
Colder spot in the fridge
Condensation on the plastic wrap dripping an slowing raise in one spot
Moved at some point, popping the center of the dough