I've never seen this many blisters on my loaf.
Is this normal?
What is this a sign of?
Extra water in or on the dough, or maybe too much steam.
(Update:) Here's Teresa Greenway on how to intentionally get blisters by brushing on water: https://youtube.com/watch?v=KeEcgmGGbBs
I gave my dutch oven a little spritz of water for extra steam so I think that could be the cause of the blisters. Thanks!
I would have guessed a lot of acidity.
Yup. Spraying water on the dough can cause this. Get a finer mist sprayer. Or reduce the amount of spray.