  For context this was a closing shift the day before thanksgiving. The store was already closed, but of course there were still a bunch of people being checked out. Also I'm not a cashier and I get to clock out as soon as I get my department clear of all customers. 

  Okay so, after an exhausting day of working in the grocery department the day before thanksgiving, me and my team member do our final walkthrough and declare grocery all clear and head up to clock out. I clock out, say bye to my girl and head towards the exit. 

  Im already pretty close to the door when i hear my name. I turn around not knowing who called it and do a quick scan to see who called my name. I couldn't tell who called me and visibly shrug (to show whoever said my name that I couldn't tell where they were). I take a couple more steps towards that glorious exit and Hear my name called out again, I turn around again to see who called me and see a cashier wave at me. 

Convo as follows: me- me, cashier-cw
  We're like pretty far away from each other at this point, i wanna say like 6 registers and a selfcheckout area away. Im not good at guessing distance, also we have to kinda yell to hear each other. I was literally in front of the exit.
CW: Hey! [My name]!
Me: yes?
CW: I need your help. Come here.
I did not want to walk all the way over there, my legs were killing me.
Me: Uh, but I'm clocked out. [Also were told that if we're ever asked for anything when clocked out to let the guest know we're off the clock. Her being a team member I thought she'd get the hint.]
CW: I know.
Me: Okay then, BYE! 
I then turned around and walked right out the exit. 

  In my head I thought to myself,  that I was tired and clocked out, and I really didn't care that this last minute shopper needed something that this cashier couldn't help with. Also she could've just paged someone on the clock to help her.

  I worked today, 2 days after this happened and asked the gal in my department if she thought i was rude to the cashier. 

  She then told me that she happened to walk by the cashier who then stopped her as she was passing (she was already clocked too btw) to ask for her help. Turns out the cashier needed help because the  guest was actually a shopper I had helped earlier. 
  (I had pulled some side dish tins from the back for the guest and went to go give them to her. She was not in the aisle she'd said she would be. After circling the whole  department a few times I gave the item to my team member and told her to keep an eye out for the guest. I still had tasks to complete. And I did them, and never saw the guest again. )
  The girl in my department then had the cashier page a clocked in team member so she could tell them where to get the tins. 

I feel kinda bad, I asked a few people if they thought I was rude. And one told me to see it from her perspective. What if I had needed help?  But, i would never bother a clocked out coworker, i always ask if they're clocked in, and if they are not I always apologize and find someone else. 

Tldr: coworker asked for help, i told her I was clocked out. She said she knew that, so I said okay, bye,  and then left.