Looks Post-Mint. Look at the B in the Liberty. It's cut into it. Since the Dime has raised edges, so it wouldn't go and stamp the face of roosevelt on it, but it was pressed hard enough to have one dime on the side of it. If it was a mint error, it would be likely that the B in Liberty would be over the indent, instead of under it.
The fact the "ONE DIME" is printed backwards on the penny, indicates it was impressed with an actual dime, as stated above. A stamp for a dime would not produce a mirror image. Further, the letters would not be incuse, but raised from the surface of the coin.
I agree with the posters above, just providing more evidence.