To have seeds you need pollen. Pollen will ONLY come from a pollen sac.
However, if you didn't have any male plants, there is a chance that one (or more) female plants hermy'd, and grew pollen sacs and fertilized itself, or a plant nearby.
Root burn or anything can potentially stress a plant enough to hermy, but there's always the pollen sac step first. It's impossible (at least to my knowledge) to just produce a seed.
I'd consider the seeds definitely worth using, the darker the seed, usually is an indication of its viability. But if the seeds came from a plant that hermy'd, there is sometimes a greater chance that any female plants grown from seed of a hermy, will also go hermy themselves.