Insurance charging a rewrite fee?

I've apparently made the mistake of switching back to an old car insurance company I was with before. They included a rewrite charge of $8.33/month, $50 for the 6 month period. I was reworking my old policy and got the price down and decided to stick with them. I canceled the new policy which wasn't scheduled to start until tomorrow. To my surprise, the refund was $50 short.

I'm in Missouri which doesn't have any laws regarding insurance companies charging these fees, but I'm not sure if I should've been charged this fee in the first place. I haven't been with this company for over a year and I have never held an auto policy with them for my current vehicle. Any thoughts?

I've switched from them to other companies a few times in the past and never seen this with them.