In this all situation one thing is sure someone know your password and used this in your absence because Stake.com cannot do this all surely someone from your side done this all for you and you have no idea about this.
The chance for that to happen is really low. We can say OP got hacked if ever the incident happened later on.
But it all happened after OP placed his bets and it just takes a minute.
It looks like a bug to me that Stake needs to address. They need to access their database logs.