Young preschoolers/hormonal pregnant mom

So I just got a call from my hubby saying my 3 year old stepson had a tantrum at the store and some lady screamed "shut up" at him. Omg I am so glad I wasn't there, I am too hormonal for that junk right now. Why in the world does a stranger think shouting at someone else's kid they don't know, and teaching our kid such a rude thing to say is appropriate?!! It's not even like we stay long when tantrums happen, usually we leave or rush thru to checkout real quick, but mannn I am glad my hubby was there and not me because it ticks me off just hearing it happened!!