Well, it's not like he met her in a nursing home, thought she would be cute when young and jumped into a time machine to go hit on her younger self. He met her as a contemporary and only relates to her as someone near his age.except I found it weird to have relations with someone from another time period. Normally, Steel wouldn't be physically attracted to a woman in her 80s or 90s, but Vixen is pretty much his grandmother,
Heck, the only way I can think to really make this feel squicky is if he'd met her as a little girl first, then jumped into a time machine to meet her when she's full grown to date her.