I don't know if it is actually "normal," but isn't that the whole point of all those types of sites. I think it's like what was already mentioned, if someone continually uses the same name across several social sites, they are certainly inviting you to search them out, contact them and also making it very easy to do.
I see no harm at all, as long as it remains a passing fancy or like Tesla attempting to make straight forward, honest contact is why these sites exist and thrive.