Rerolls won't change the genes the horse has. You can't reroll a buckskin to bay. You can only get different variations of buckskin by rerolling a buckskin
Mystery chuckled "Well bye!" then looked behind to see him further behind, she felt bad and slowed till she was closer to him "Is something wrong? I don't think i've seen a horse gallop that slow no offence" She asked/said softly not sure how he'd respond