It's okay to leave it in there (but only if it's f/t)--my female won't take it off tongs but she'll eat it if left overnight. Just check it in the morning to make sure it's gone and that's all you gotta do. I actually find that easier.
All of them have different preferences, my boy won't touch it if I don't heat it up and do the zombie dance so to each their own. As long as he eats it, it's fine. =)