I don't know the answer to your question, but have one of my own: Would being on a bookshelf give it enough light to do well?

@socks Good point and that might argue for putting them under a spotlight if kept inside.

it is probably a stray seed that got into the seed mix. outside would be good. keep an eye on it ... it may be something special ... like an arabicum

it would be okay if you are overwintering it ... don't give it much water at all over the winter. Get it outside in the summer.