Where's my momma gone?

Today was very strange... for the last few days momma has been gone now and then, she still pops by many times during the day to play with us and feed us, but now and then she's not here... and today I saw her leave... I started meowing and scratching at the door like a mad-cat... and momma came back and gave me a right old snuggle, before popping out again...

I'm very puzzled...