No, it was sitting by itself for quite awhile, maybe the way the light was hitting it.
Hi Casey. Thanks for posting this. We need more eyes on what's happening in the nest box. It doesn't look good for the hatching of the #4 egg. But, you never know.
Also, unhatched eggs have been known to explode. It happened in the Utica nest box in 2020 and I've heard of it happening at other nest sites. Thankfully, that has never happened here, yet.
Congrats on your first post! Welcome!