It wasn't *that* petty. First of all, Alexis had ordered the gardener to cut her the last of the roses. She was giving commands to what was no longer her staff, and yet she was more readily obeyed than Krystle from the previous season. Secondly, by then, several months (if not a year) had passed since her "panic attack" happened; Krystle had gotten used to having servants. So her being miffed about the situation feels pretty natural.