There were two.
Both exactly the same, with the lower 2/3 of the bud still seemingly perfect, but the the 1/3 above the rot area dry and turning golden brown.
All other buds look powerful and strong, but I'll be watching like a hawk.
I'm wondering if I may have induced this in the process of my PM chase.
I've been using the diluted milk spray, which seems to be effective temporarily. I try not to hit the flowers at all, but a couple of times I got single buds a little drenched by accident.
These plants are just stacked with dense flowers.
They seem so close to done that I'm worried about waiting too long, but I'm only at about 4.5 weeks flowering.
First time, lots of effort, don't want to mess this up.