I don't know what the issue is. However, before you do anything you feel is drastic to your substrate, try just poking it with a BBQ skewer/chopstick. Every time I have had a substrate issue, it would have a nasty smell. You may have air bubbles as well, should only be concerning if it smells nasty as with all that H2O2, it wouldn't be surprising if you have air bubbles trapped. I am not saying that this is an end all test, but if you get a nasty smell after stirring it up slightly, that does mean something is wrong, and you don't have to tear up what is there.