I found a bug in the old comment style..

alias test {
if ($version == 6.1) { ;this comment will be sent to the server }
else { ;this bug doesnt exist in your version }
}

it seems if a comment is between { and } on one line, it will be sent to the server. I dont recall this happening in previous versions.

AFAIK mIRC comments have always had to be at the start of a the line. If not, they do now (see /help Comments).

/me shrugs

i tested a script that worked fine in 6.03, but in 6.1 the comment sends the command.. it might cause some problems with tutorials out there, but i dont know

No, there was another post like this about a week ago and mention was made that the comments needing to be on a new line. I would say that if you wrote a script that allowed the comment to be on the same line as a command then this would be a fluke more than mIRC purposefully allowing it.

Or perhaps he did something like

if (blah) { do something | ;this is a comment }

mIRC seems to treat | as starting a new line.