I think there is arousal thinking about being your true self. I think cis-women get aroused when they feel good about themselves, when they are in touch with their sensual side (not necessarily sexual side). Why wouldn't transgender women not get the same feeling. It is just that in preop trans women the penis is still their to react. This is a doubt causing situation for someone who is not penis oriented. It can cause stress, but in my opinion it is normal. If feelings only go as deep as getting aroused sexually only, then I would question being transgender.
Moni