But how it's possible that someone logged one minute after me. I played here today first time since a longer period of time and haven't told anyone about it. What's the probability that someone logged in the same time like me instead 30 minutes before, 2 days before etc..
I don't know, but you're very lucky that it wasn't a big sum of money. I think it makes sense someone would log in right after you. Say, it's a keyboard malware tracking the buttons you press. Then it would be logical to act on it right after you've logged in so that no time is wasted. This is very alarming, and I am sure Stake will say something about it, but it's not likely to be a trouble on their side... Just check your PC for malware using at least two antivirus system (perhaps one of them would not catch what the other one can). And avoid typing in any passwords and logins from that computer until the mystery is solved.
And never even use the same log-in and password for two different things, it's a big point of vulnerability.