Seeds germing while still on plant

So today I was picking mature seeds off my seeding plant, I noticed that there were about 8 seeds that were starting to germinate while still on the plant. (like still in the calyx). Outdoor, trainwreck/diesel. I'm thinking that the seeds germed as a result of rainy conditions recently. I have since moved the plant under the eave to keep it dry. The plant is pretty much past "done" as far as harvesting is concerned, but I've not cut it so as to get maximum seed production.
Not my first grow, but first time trying to make seeds.

Are these seeds germinating while still on the plant a common occurrence? The parent plants exhibited good genetics, (fast growth, good structure and spacing, bud production.)

Ive moved the germinating seeds to a paper towel to finish germination btw.

Appreciate thoughts on this as I have not seen this before.

Wow, that's crazy. I couldn't tell ya whether that's normal or not, but it's pretty crazy.

Not really crazy or bizzare. Normal plant doing all it can to reproduce. End of life cycle it knows it is dying. Given heat and moisture mature seeds are going to sprout. No dirt or napkins required.