The problem here is that BufferedResponseMapper is wrapped as part of SystemMapper in CryptoMapper.
Later when mountPage("/home") is called a new CompoundRequestMapper is created with CryptoMapper as an member and a MountedMapper for HomePage is prepended to it.
So we have : CompoundRequestMapper(MountedMapper(/home), CryptoMapper(SystemMapper(BufferedResponseMapper, /* other system mappers */ )))
When a request with url : home?0 comes MountedMapper(/home) matches on it and BufferedResponseMapper is not asked at all. Later when starting to render the reported WARN is issued because now we check for stored response.