Most folks who shop at Petsmart know that if you have a Pet Perks card then you need to show it or mention that you have one but don't have it with you. Being that you went to make a payment with your debit card without inquiring about the Pet Perks card prior to that probably gave the cashier the impression that you did not have one.

Out of curiosity, during your phone call, did you even address the cashier? Did you even look at her? If you didn't say a word to her and were completely involved in your conversation, I can see why she didn't speak to you. She didn't want to rudely interrupt your very important phone call. If you refused to acknowledge her and were carrying on a conversation on the phone, she probably figured you weren't interested in speaking with her and she proceeded to do her job which was ring up your items.

Quite honestly, it sounds like the cashier was treating you as you were treating her. You basically ignored her and she decided to basically ignore you. I have a feeling that if you would've told the person you were on the phone with to hold on a minute, said hi to the cashier and were involved in the checkout process, it would've been a much more positive experience.