You didn't describe the changes you made. Good chance the thing that changed was the location of your thermometer probe. Just a small change in that can give you a very different reading. It's possible you may have had hotter temps than you realized all along, but didn't notice because the probe wasn't in the hottest spot. Or the amount of substrate insulating the UTH changed? You said you made changes for the sake of humidity...was one of those changes to reduce the amount of ventilation? That will not only hold in humidity, but heat as well. It could be any number of things.