I don't think the WB is off, I just think the BG is not pure white. I could be wrong but it doesn't look true white, it looks slightly mottled, like a painted surface.
Lovely clear detail throughout here Nellie so the lighting has worked really well. I would agree with Jack that the BG could easily be made white and I think it might help but it's a lovely shot and I like the angle across the diagonal.
Well done
Rob