Glad you asked the question as I have one as well. I'm not trying to hijack your thread (no pun intended, lol) but do have a similar question.
I'm in the process of hand quilting a baby quilt. I only noticed last night that for one of the elements, I've been using a silk thread vs a hand quilting thread. How did I not notice this?!? Do I need to rip out the silk thread and re-do with a hand quilting thread?? I've been hand quilting for years and have never done this before!