Nope - it's not a stupid question at all.
I'm afraid the "why" is simply that our auto-mod system has recently developed a mind of its own and is moderating perfectly innocent posts for no apparent reason. :o It's nothing personal, I promise. And I agree it's particularly daft when it stops you posting in your own thread, but I'm afraid you're not the only member to run into that problem recently. We're really sorry about this, and know it's frustrating, but there's not much we can do about it. As you may have read, we're in the process of moving the forums to a new platform, so at this stage there's little point in putting any more effort into trying to fix the glitches in this one.
I've approved your post now. We do try to deal with moderated posts promptly, but the moderators are all volunteers, so there may be times when they're a bit thin on the ground and it takes longer to get round to things.
Hope that helps.