My Cat Loves To Play With Her Tail

My cat Pearl just loves to play with her tail. She's just started doing this for a few months now. I never remember her doing this as a kitten and she just turned 5 years old today. Do you know why she might be doing this? Is it a sign of boredom? Some time I need to get a video of this because it looks so funny.:)

It is funny you posted this because I have seen my Mama cat do this recently and she never did it before that I can remember. I think Mama is about 4 years old now. It is pretty funny to see but I honestly do not know why they do it.