1833 Letter From Lancaster Ohio To Hocking County Ohio

Hello,

I am a newb when it comes to stampless covers and wonder what I have with this cover I just bought. This single lettersheet was sent in 1833 from Lancaster Ohio to the county clerk in Hocking county which is about 18 miles away.

It has a "12" on it which is presumably the post-paid rate. I know the rate for 81-150 miles was 12 1/2 cents, but the markings indicate 12, not 12 1/2 and unless I made a mistake, the single lettersheet rate in 1833 was 6c. Can someone help me understand what is going on with this cover?

6 cents for not over 30 miles, thus your cover is a double-rate and had an enclosure.
It is not marked "paid", thus is was sent collect.

Awesome - thank you. As I read the contents, it actually mentioned an enclosure. The contents of this one are interesting. . .a deposition about adultery.