I think the speuters are always a little more rough on the older guys and gals. I've heard that females that have been bred sometimes need an extra day or two to recover. Clifford had a really hard time after his neuter and had a lot of scrotal swelling...poor guy!
Give Tully a gentle hug and kiss from the brindle bunch around here.
You never know when it will strike, but there comes a moment at work when you know that you just aren't going to do anything productive for the rest of the day.