Sorry, Amy! I don't think it's rude to politely let someone know if they are doing very poorly at their job, similarly to how you would compliment them if they were doing an exemplary job. I'm confused, though, the woman who checked you out was part of your play group? Or another customer was and she overheard it? I do think that it was rude of HER to call you out on FB. If she really did think that you handled it poorly, she should have messaged you privately.
I don't think I would quit the group, though. If it were me, I would purposely go and be friendly and nice...you know, "kill them with kindness"
