Was I rude?

Finished checking out groceries in self check out for a customer on instacart and the customer had a question so I started texting the customer. 2 guys that were buy a cake asked me if they can check out and I told them that this register doesn’t let you register anything until I finished bagging the items, they said ok and moved over to the next self check out. I was still texting the customer and one of the guys came back to the self check out register saying I was rude for not starting to bag, so I told him there are 8 other self check out registers he can go to. Then he walked away. I wanted to know if I was rude for not starting to bag, when I was answering my customers question on my phone.