Likely. I have both of Darden's new HIT books and he advocates "superhydration": drink 1-2 gallons of water daily. 1 gallon of water is around 8 lbs. You also said in your original post that you don't work out constantly for more than a few months, so it sounds like your body is just responding to actually being on a stable training program/routine.
Sky, I tried bulking and HIT earlier this year. I didn't keep careful records so I'm dieting down now to see if I actually gained muscle mass, but I feel like I gained more fat than muscle. I think it is because I was always either sore or injured and couldn't train more than twice a week. I notice that if a body trains less frequently, it is more prone to collecting fat while on a bulk.
So if you are the kind of person who learns from others' mistakes:
-Go ahead and train even if you're still sore, just use lighter weight and go NTF or even below that. Forget Darden/Jone's advice. Of course if you're injured you're better off stopping.
-Be sure you're not taking too long between sets. Keep a watch with a second hand on you if needed.
-Keep a food log. FitDay is helping me big time in my fat loss so I plan to clean bulk and on a split routine to gain size again, the better way.
HIT is a great program for fat loss or physique maintenance. Most of the bodybuilders in the Darden books that you read about did NOT use HIT to bulk or achieve their initial size, but they used HIT to refine their physique for contests.