I have observed similar effects from enforced rests, and that weight gain does not appear to be all that closely correlated with calorie intake and exercise in the short term.
The improved performance after rests seems to me to suggest that muscles take a while to process the benefits of exertion. Conjecture: it actually takes a long time (days? a week?) for the construction of new/improvement in efficiency of old muscles to be effected. In the meantime, it seems almost as if repeated demands on the muscles slow this improvemnet process down.
About weight loss, the fluctuations I notice are more in the region of four pounds, which I always attributed to variability in water retention for hormonal or other reasons. I've never figured out what effect, if any, rest has on that.
At any rate, enjoy the quantum leap in Can Do!