ignoring women when you break up.

I was dating a girl who really liked. We broke up. About a week after she sent me a text message. I did not reply. A couple of days later she calls my home phone wanting to know why I was ignoring her.
Another girl called and when I told her what I was up to she (hanging out with friends) said " You never did that when we were together. She seemed upset I was so busy. Is this common?