Trusting your mechanic

Before driving north the other morning I took our Volvo S40 into the garage because the left hand tail light was out, and the left hand turn signal was clicking in double time.  The latter had been happening a couple of weeks before (when the left headlight was out), so I assumed the mechanic had somehow not fixed something.

I got there right when they opened at 7:30, because I needed to drive 540 miles that day, and Graham had told me very plainly that he didn't want to get to Grandma's house after his bedtime. I thought it was great he was so clear with me.  I described my problem, handed over my keys, and sat down to eat my breakfast biscuit from Sunrise.  I ate and read, but by 8:40 I was feeling a little nervous.  Was there something systemic that they were trying to diagnose?  So I went up and asked the guy what was up with my car, he went back, and then came out and said it was almost done, he'd ring me up.  $15.33.  They just needed to put in a bulb, which they didn't have on hand and had to have delivered from a parts store.  Turns out, the fast blinking of the turn signal is just meant to tell you that a bulb had blown out.

So here's my question:  why didn't they tell me that from the outset?  I was sitting there nervous, thinking something might be wrong and that maybe we'd need to drive north the next day, when the hold up was all about needing to get a part delivered?  So did they not tell me that because they like for you to be nervous, and then to be relieved to find out how cheap the repair was? It's not like they're making a profit on a fifteen buck repair.  If you charge that little money, it's purely a relationship management play.  You want the customer to appreciate your honesty.  So be freaking honest.  I probably wasted 15-30 minutes concerned about what might be going on. If I could have had full concentration during that time, I would have been able to read and retain more.