That's part of it yeah. But, at least in my experience, that tells me you pushed code (to disk) and didn't load it. You could probably just notify at 4 am every day if erlang:modified_modules() /= []; assuming you don't typically do operations overnight. No big deal if you're doing emergency fixes at 4 am, you'll get an extra notification, but you're probably knee deep in notifications, what's one more per node?

But, that's not enough to tell you that the code on disk doesn't match what it's supposed to be. You'd need to have some infrastructure that keeps track of that too. But if you package your code, your package system probably has a check, which you can probably also run at 4 am.