Dear Madlen, it is a good questions nowadays there is always some trolls and I suspect it is the same person who just randomly downvoting the people, the person does not care and just there to irritate the people. Just ignore him, you will never receive any explanation and just will be upset, the best to ignore as his upvote is so low that will not cause anything.

I hope seeing you around posting and being active, it is a time of Up or Down-votes. it is just early beginning I hope with time it will stabilize and those people will just get tired and give up if they will receive no attention from others. I wish you a nice day and see you around :)