I am not sure if you saw that, but I am always watching everything when I am analising something on CoinMarketCap.
Steem Dollars supply was around 3,5 M one week ago. In the morning I took a look on the circulation supply of Steem Dollars and it was around 4,140,638 SBD.
If you are taking a look now you will see the supply increased with over 30,000 SBD.
I believe the creators of Steem Dollars are releasing a low supply daily in circulation so the price of it will be back to $1.
Maybe I am wrong but this is just an assumption.