Another possibility....you might be replacing fat with muscle. Muscle is denser than fat; it's possible to GAIN weight while improving your "shape" and your conditioning. Some fitness gurus tell their clients not to focus on the scale and instead judge themselves based on how their clothes fit them.

Missed my commute yesterday. The baby was sick all weekend; I had to take her to the doctor, then babysit her all day. Good to be back on the bike today.