If it is happening just after a cage clean she could be re-marking the cage with her scent, my old hammy Buffy does this and apparently its not normal for girls, but hey thats Buffy for you. If you touch her back end does she stick her tail straight up, she could be in season. If you are at all worried about her being ill though I would go back to the vet or at least ring them as small animals can go downhill very quickly when they get ill.

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Mum to:
Sam & Lucy (human children)
Henrick (GSD)
Syd, Dizzy, Elvis(Cats)
Harvey, Mojo,Freckles, Nobby and Sugar(Mice)
Snakey-Lakey and friends(Fish)
Remy, Fidget, Rommel, Monty and Edd (dumbo rats)
Spike, Cordelia,Willow,Fred,Xander, Angel, Darla (hamsters)
A place in my heart will always belong to my babies at the bridge.