I always send the maintainer a 'thank you' afterwards telling them that I've moved their package to [community] and asking them if they have any specific advise about the package. My personal opinion is that it is not necessary to ask beforehand when moving a package simply because in my experience it can take quite a long time to receive a response for such matters.
But I think that not giving any indication to the maintainer of an AUR package that you have moved it is rather rude and not conducive to the general idea of the community. --Kaiting. -- Kiwis and Limes: http://kaitocracy.blogspot.com/
