I would give him another try. His reaction to your situation would make me consider it. Sadly mistakes happen.

I once spent a whole day working on a friend's car and mine - we replaced front suspension on a 7 series and an M5. Probably took us a better part of 10 hours. When we were done, we then headed from San Francisco to LA - about a 6 hour drive.

We drove side by side as the roads were empty at about 80 MPH. He pulled over one time to check his lug nuts just to be sure we torqued them down right.

Next morning in slow LA traffic, I felt a slight wobble from the right rear. I pulled over to check and three bolts were literally sitting in the wheel holes, one was loose and the last one hand tight. Check both rears and YUP! I was the one who forgot to torque down my bolts! I could have killed both of us had a wheel come off during our drive down.

Sometimes, crap happens.