Red is a dangerous color to use in any tool--we're sort of hardwired to think 'ERROR!!!' when we see an icon left of our code in red. When it's not, it mutes the effect real errors in red should have.
For some reason, whenever I use a lambda in Java 8 I get a red mark to the left of my code. Is this an error or warning icon? I don't thinks it is, but it seems to confuse more than a few folks: http://stackoverflow.com/questions/37922829/intellij-idea-overrides-method-warning-with-java-8-lambda-expressions
It may be useful to have this, so I don't want to disable the icon totally in the preference, but any chance you can suggest to your UX team to change the information gutter lambda icon to a color like light purple or grey--or any color not associated with FIRE :)