This also makes me think of my dad. I'd sometimes call; my mom would be out, and he'd answer the phone, and be a bit pissy. I'd ask him what was wrong, and he'd say "I was in the middle of something!" Well then, that's what voicemail is for! And he'd grumble, and then turn into chatty charlie! It was just so funny since if he didn't answer, it wasn't a big deal at all!
Like I said, I call my mom every day, or she calls me, but sometimes its just "hi, how are you, how was your day, ok bye" And if I'm not home, or she isn't, many times we don't even leave a message unless there's something we need to tell each other.