It all depends on where the message occurs. If the message is next to their address then it means little because that is just the "Full Name" setting in a chat programme. Some chatters just put that there it make the 'whoisers' out there wonder about it all.
If the message was in a private or notice reply then the user you whois'd is likely to be an oper as they are the only ones that can tell when you do a whois on them. They get the message via a server notice and could script an automated reply via that.
