Anyway, I need to be extra observant about the growth stages, and even though I tend not to cull but let seedlings grow out, I may have a situation that requires culling — I’m more of a believer in Murphy’s Garden Law that you should grow extras because if you don’t they’re more likely to all die from unexpected mishaps....

I now have eight (8) Bill’s Striped seedlings “from the #4 plant”, individually potted in tiny-small containers. (They are not all in these photos — the others have been moved off the heat mat).
But one of them caught my eye —red-circled seedling photo’d on 3/29 (left) and 3/31 (right)

... you can see how the cotyledons are folded upward. I was intrigued/concerned that they seemed to be stuck together, so yesterday, I sprayed the leaves well, then tried to ease them apart... and found out they are actually stuck together — fused — I ended up tearing part of the fused leaves before realizing. Today, there is a tiny true leaf pair starting to push their way out sideways to grow from the base of the fused cotyledons.
This is almost exactly what happens when the very tip of seedleaves are stubbornly stuck in helmethead/seedcoat but the seedling is otherwise healthy.
I investigated further and found two more Bill’s Striped seedlings doing the same thing.
...so .. I think these will grow out of this phase once the true leaves grow and eventually drop the cotyledons — but I’ve asked the project group if I should cull them. ...What do the members here think? Also, have you encountered seedlings like these or any other notable defects?