Skin of Sourdough Peeling Off

Hi everyone!

I've lurked on this site for quite a while poring through discussion after discussion and troubleshooting my own sourdough along the way. Last night, I've finally baked sourdough that tasted delicious! 

Now with that being said, I noticed something really interesting when my boule came out of the oven. The skin seems to have not only broken, but it looks like it's peeling off somehow (see the singed bits near the top of the loaf in the pic). Would anybody have any idea what's causing this? It's not necessarily a problem as the bread was still great but just curious what is causing this. Crumb was fairly open if that offers any clues. 

Recipe:

• 400 grams AP flour
• 57.5% hydration
• 1.25% salt
• 40% starter

Process:

1. Dough was hand kneaded until the window pane was very thin
2. 2.5 hour bulk fermentation at ~75-80F 
3. Stretch and fold
4. Another 2.5 hour fermentation at same temperature
5. Folded Everything Bagel seasoning into dough
6. Shape into boule
7. Dust with rice flour
8. Placed into a covered bowl to proof in the fridge overnight (~12 hours)
9. Took it out of the fridge and rested for half an hour, scored, and straight into preheated oven
10. Baked for 20 minutes @ 500F while covered by an upside down bowl in the oven for steam
11. Baked an additional 20 minutes uncovered @ 450F
12. Let the bread sit in the oven with the heat off and door cracked open for 15 minutes

Another clue is that by the time I take the bowl off during the baking process (end of step 10) the "peeling" had already taken place.

Any and all thoughts/comments are appreciated!