In my opinion... I think its a little strange, but that's just how I see it. My husband is aroused my anal stimulation, however I don't believe he'd ever want me to pretend to cum in him with a strap on, on.
Is this something that you are comfortable doing with him, are you aroused by taking the man's position? By taking this roll does it make you feel "gay"?
If you are aroused by doing it and don't feel "gay" then no I don't believe you should suspect him of having those feelings.
But if you are not comfortable with doing it you should talk to him about it.