Jack and Chloe groom each other; sometimes it ends in a fight, sometimes they just take turns grooming. I don't worry about it when they tussle. They were raised together, and, although they're not littermates, they're like brother and sister.
Mine don't tend to fight after grooming. Occasionally one will get up and run off when they're tired of grooming, but not usually. They play wrestle/fight every day, but it's more common for wrestling to turn into grooming than vice versa.