I dreamt I was at a supermarket and the self serve machines were messing up

Claire Kincaid from Law & Order helped me out and showed me how to use the machines, even though I do know how to use them. I felt like she was talking down to me, although she was only trying to be helpful. I then realised I forgot something, but just let it go. I was completely docile and felt so dumb. What could this dream mean?