I've noticed this a couple times recently:
At night, I put in a cucumber slice for my BN pleco's dinner. Once it's in there and the pleco (Jeeves) starts eating, his
betta tank mate (Andre) will kind of stalk and observe Jeeves as if he's waiting for something. Eventually, a cucumber seed will get loose and start floating around in the tank. Andre chases it, plays with it, tries to eat it, etc.......gets bored with it and goes back to waiting for Jeeves to knock another one loose. Maybe I'm crazy or way too easily amused, but there's something about the way Andre waits for it to happen, like a dog playing fetch, that's so fun to watch over and over again.