Something strange with the minting.
Few hours ago, I had some coins on stake which generated some minted coin.
However the block orphaned.
Then 10 or 15 min later, a new block was generated (same stake I guess) this time accepted.
How many time will it try to mint coin if a transaction doesn't get validated ?
It will keep try again and again, and, due to the coin age, you will get the interest.