As with most things, Chase just went with it. He's very mellow about new things and new experiences. We also road the bus over to the veterinarian's office. I weighed him and he came in at 59 pounds (compared to 63 pounds when we left Guide Dogs in July).
I called Guide Dogs' support center, and Beth said to feed him more. So he's now getting four cups of kibble a day instead of three. I'll weigh him again in a couple weeks.