"Extreme rudeness"? "Deeply offended"? What hypberbole, not to mention an attitude of entitlement.

Did you find what you needed/wanted? I'm guessing you did, you just wanted to be ASKED that, even though you didn't need the help. Get over yourself already.

When I worked retail, sometimes I was so engrossed in thought ("How should this display be set up?" "How can I re-work these four rounders of clothes so that the clearance signs will be the most accurate?" "If I move these here, and move those over there, does that work with the new seasonal stuff that is coming in on the truck tonight?") that I sometimes was oblivious to customers. However, even though I was "backstage" (marked items down to clearance, set up sales, etc.) and not in the actual sales end, if a customer asked for help, I stopped everything I was doing and did whatever I could to help them out, and they appreciated that.

And you, sir, would not have deserved that treatment. "Will not be setting foot inside a Petsmart store again?" Lucky Petsmart. Please stay out of my Petcos.