That is what my elderly cat (14 years +) does frequently, like a caged animal wanting to keep her step count up. It's exhausting to watch her! I think she does it when she's hoping to be fed. It also means that we're in danger of tripping over her, because she tends to follow us around, and stop near our feet. If she gets on to my lap, she doesn't stay there for long - after a minute she'll be pacing again.
Does anybody else's cat do this? It seems to be fairly new behaviour.