NHD-0216CW-AB3 displaying wrong chracters

[The Fat Bastid]

I have a NHD-0216CW-AB3 hooked up to a arduino micro being fed via bluetooth from a raspberry pi (running jessie) python script.

It has been working fine but I just noticed that 2 chracters display the wrong thing.
Instead of a capital W i get a curly bracket (first attachment)

And instead of a degree symbol (°) I get 2 characters. the little house thing then the square arch thing (2nd attachment)

The rest of the alphabet in either case and numbers come out correctly. (haven't tested every symbol)

I'm using rom set a. The W doesn't change position in any romset so i'm not sure what it thinks it is doing.