This is caused by 1 of the /etc/DIR_COLORS setting and tells you the file is executable.
The part of DIR_COLORS I'm talking about should look something like this:
# Extra command line options for ls go here.
# Basically these ones are:
# -F = show '/' for dirs, '*' for executables, etc.
# -T 0 = don't trust tab spacing when formatting ls output.
OPTIONS -F -T 0
Hope this helps.