Soooooo.... the same thing happened today, but this time Sunny went over and started nipping at Mars' beak and Mars backed away. I wasn't there to see it, but my kids were. They think that Sunny was attacking him, not playing. Again, this is Sunny's cage so he is protective of it, we will have to try and arrange a meeting time on neutral ground.
Mars still doesn't like to be handled, so it makes it a bit more difficult. The plan was if they didn't get along was to have Mars go with my son and Sunny go with me.
I hope things will improve over time... We just had such a good experience with Sunny wanting to be handled only after being with us for about two weeks. Mars will eat from my hand, but he won't go on it to eat. From what everyone has said here in the past I just have to be patient.