What does this mean and should I be concerned?

I was watching YouTube on my iPhone when I randomly got this message. "A server with the specified hostname could not be found." I googled this and found that people who've gotten this message were trying to set up "mountain lion servers". I have no idea what those are and have never done anything like that on my iPhone, does this mean my phone could've been hacked or something? (I have not jailbroken my phone if that makes any difference) What should I do?

It means your device was trying to access something it couldn't find. I wouldn't worry about it.