Urgent: found this in the tranny pan

[B 4 You]

So I'm changing my transmission filter and fluid, and when I took the pan off I saw something interesting. Magnet was a little dirty, but I cleaned it. No shards of metal. But I found a bolt... a semi-long bolt with a 4 on the head. I can't find any open bolt holes. Where on earth did this come from? I think I'm just going to put it back together and take the bolt out. I have no transmission issues other than a 1-2 hard shift. Even Nate drove it and said it shifted flawlessly. I'm confused.