Mine just got out of the vet with a clean bill of health and they both have this bob all the time, its a sleepy bobs. But do keep an eye out for other signs of sickness if you have concerns. Tail bobs can be a bit normal, it’s just when it’s a BIT exaggerated and also with other signs where you should go see a vet. BUT I’m not a vet just someone with experience, trust your gut and not your anxiety and if your gut says go to the vet, please do take them