It is normal, I've had days where I've ignored my own family and snapped at people and even left the phone ringing cause I feel so damned miserable. The only explaination can be hormones, the hospital actually warned me that it could happen and I'd even mentioned it to my family before the op just in case. It's not nice, but I think it is temporary, our bodies are going through so many changes it gets a bit confused as to what is happening.