Stem Color - Phenotype?

[JetStar1]

So I generously received some Brandywine Sudduth seeds in both a SASE and the MMMM. As I planted the seeds out, I noticed RL and PL seedlings in one batch (kept the PL). In the other batch, I see different stem colors. Two of them are red and one is green.

I have a couple questions. . .

First, is stem color even a phenotype, or something that I should be looking at?

If so, . . . What is the expected stem color of a true Brandywine Sudduth (most of my other Brandywines are red?

Finally, assuming red is the expected stem color, . . . What should I do with the green seedling?