When you finish a mission in Town --> Activities --> Missions and you get some exp, the tooltip that comes up if you hover over your level doesn't update until you navigate away from that page.
You get the exp, it doesn't cause any problems or anything. I just thought you might want to know.
I was using that tooltip to see how much exp I needed before leveling up to make sure I bought everything I wanted before a new selection appeared on level up and noticed.