Gaining muscle mass without working out?

I started taking my fitness more seriously last February, and since then I experimented a little while with SimpleFit, then switched to Convict Conditioning when I was unhappy with the results. I kept up with it for a while, but stopped due to a period of poor sleep (~3 hours/night, didn't want to risk injury) about a month ago and failed to pick it back up again once I'd recovered.

My question is, since then, I've gained noticeable weight, and it appears to be muscle. I find my arms and calves to be more noticeably defined than they were a month ago. My first thought was weight loss, since less fat would mean muscle definition would begin to show, but this is not the case...I'm 2 lbs above my weight a month ago, and at a lifetime high weight for that matter. Not only that, but I feel stronger, and people have commented on how strong I am a couple of times recently.

There are only two things that I've changed that could be related, and I'm curious what this community thinks is the cause, or if there is some other explanation. One, I increased my protein consumption (milk, peanut butter, whole grains, beans, and occasionally even meat), and two, I have been curbing my caffeine intake for the last couple of weeks from 100-200mg/day to less than 5-60mg/day depending on sleep deficit. I interpret these "results" to mean that 3x workouts a week may be too much for me, and I should work with more rest time, possibly going down to 2x or 1x even? I was doing nearly 60 minutes of modified CC (/r/bodyweightfitness has been a great help in developing my own method) a day, three times a week, FWIW.