Modifying RSS2 native function notification

I have read that when you publish and unpublish then publish the same post it will notify your subscribers twice for the same post. We are changing the look and feel of our blog and want to unpublish some of the post then republish them without notifying the subscribers. Is there a function I can add to my functions file that would check to see if there is a post date. Here would be a sudo code idea.

if (post->date < current date){
Then don’t notify subscribers
}else {
run notification as normal
}

I currently don’t have a plugin managing my rss2 feed subscription button just the wordpress function.

Thanks for any help.