Ethicality and the Ethical Ethics of Implementing It

I am familiar with the phenomenon of people not fully charging pastors, reverends, and clergy for things. We have good friends here who picked up dinner for us one night (a semi-big deal as the drive to the restaurant would be an hour+ for us) and didn't want to be reimbursed. Avraham and I were very quick to point out that if they refused to take our money, we would no longer be able to ask them for the favor of picking up food for us. Now, this was a favor, between friends, but part of what they were thinking was that Avraham is their rabbi. As such, we were both uncomfortable with having them pay for our food (side note: if you ever really want to help your young rabbi and his wife, take the kids to the library so we can clean up a little!).

Today I went to get the side mirror on the car fixed (yes, I smashed it into a mailbox one morning while driving too quickly and angrily on our winding street). I went to a business owned by someone who is, I will say, a satellite member of the community. He used to be more involved, his daughters went to the Hebrew School, and we met him for the first time at a meal in the sukkah at shul.

He replaced the glass in my mirror, replaced the wipers on my car, and scrubbed my windshield (we've been having a very bad problem with streaks when it's raining lightly). I went to pay, and he said that he couldn't ask the rabbi to pay. I paused, unsure of how to turn down his generosity without sounding like I didn't appreciate it. I said (a little cautiously) "If you don't let me pay you for the repairs, then I can't really come to here again for service." He thought about it for a second, and instead charged me cost for the items, not for labor (I suspect he cut a few dollars off the price as well, having talked to my father and uncle who are 3rd generation in an auto parts business). I accepted and paid.

First, I will never quite get used to be referred to as 'the rabbi' by extension. It's definitely part of my life, and one I'm aware of, but given the way our community works, I'm primarily identified as the mother of my children (when not being identified as just myself) - school, dance class, gymnastics, etc.
Second, did I do the right thing? Am I allowed (halachically, ethically) to not pay him for the labor he (personally) did, at his insistence? I fully understand and appreciate the desire to give to the rabbi and his family, but it feels wrong. It's like when people give us large checks for Chanuka - it means a lot to me to know that we mean a lot to hem, but it also feels wrong to accept it.

Thoughts?