It seems a common enough experience for people with some expertise in some area to be frequently called upon by people they come in contact with to use their skill to help with some small thing. Is there a word or phrase that sums up this experience?
Anyone with a computer to a computer tech: "Hey do you know why my computer is doing X, and can maybe take a look at it while you are here?"
Anyone with a car problem to a car mechanic: "It's making this noise. Do you know what that is? I have it outside if you want to hear it in person."
Anyone with a physical ailment to a doctor: "My X is giving me problems like Y and Z. Do you know what that might be? Should I be worried?"
I'm looking specifically for a situation where the specialist is not intending to be performing their skill, and aren't being paid for it. Usually they are a friend or acquaintance of the person who is asking.