UPDATE APRIL 2016: Pippin made this noise only twice, after which he was very happy to be held and handled. I am certain he was just a bit scared and frustrated at being prevented from doing whatever he wanted to do. He was never mistreated, and died happily of old age.
ORIGINAL DESCRIPTION: I’ve had him about a month. I took him out this evening while I cleaned his cage and he was happily rolling around in his ball for about ten minutes. When I took him out he trundled around on my bed for a bit and then started making this noise non-stop. When I got the camera out he quieted down a bit, but by talking to him I could make him do it again. I’m wondering if this noise means anything other than ‘I’m scared’? I didn’t do anything different with him, so if he is scared I’m not sure what has caused it.