Normal
As I understand it, and i'm very happy for someone to tell me i'm wrong, the reason for calibrating your battery is to ensure that the reading you're being given of your battery %, time remaning, and health are accurate, and not for improving battery life/health as you'd hope.
Unfortunately, if you've calibrated and it's telling you your battery health has decreased, then it's probably a truer reflection of your battery's health than you had previously.