no, by writing similar \ equal code somewhere that later other people looking at it could argue is a re-use of the GPL code they looked at and thus causing the whole project to became GPL.
it is just them thinking it is better being safe then sorry. if they don't even look at the code there is no way to argue that they are copying it.
Just a small correction/clarification - using GPL code inside a non-GPL project doesn't magically cause it to become GPL, it just means you would be committing copyright infringement if you distributed your project afterwards.
It's still something you want to avoid, but the outcome would potentially be a lawsuit from the copyright holder, rather than forcing you to relicense your project.
it is just them thinking it is better being safe then sorry. if they don't even look at the code there is no way to argue that they are copying it.