Yes, because there are some malicious imposters that copies the names of established members here and some people who receive the message are too lazy to even check who sent them the message. Surprisingly, there are still people who are scammed by these imposters that's why that warning is there. Don't worry, when you hit Jr. Member that warning would be completely removed.
For more information, check the Meta section of the forum.
you are right dude, it is a warn for other members to keep wary with newbie due to they are still new in this forum. it could be scam or something like that.
when newbie reach up 30 activities , warning like that below your message will vanish. now you are only have 15 activities double it than all wil be looks so nice