It's the profession though. Everyone needs a mechanic, It happens to us all. You don't talk to someone for 5-6 months and then they call to ask a favor.
I take it as a compliment. They need your skills to figure out a problem that they can't.
I offer free advise all the time, but don't take it personal that people need car help.
Hell I will go out of my way to help people fix things they can't afford to fix.
Sounds to me like the mechanic thing is turning into a job only for you, and not a hobby.