It sure looks like Chip found something HC to munch on or those yellows were a high before a break.
BTW, are you sleeping at all? It looks like when Chip is surfing green, you're testing hourly. If Chip's nadir is pretty reliably at a certain point, you may want to factor that in to your testing so you can get some sleep. It's important to make sure Chip is safe but it's also important to take care of yourself.