RM:
In banking, we refer to the start-up period as the "stabilization period"...in other words, it's a tenuous balance.
I encourage you to be a walking billboard (so to speak). Don't have a "we've built it, now they'll come" attitude. Go out and bring them in...somehow. Remember, the retail business is selling...and you have to sell your LBS in a competitive world.
One of the ways you do that is to create an incredible customer experience (as you've done with this guy) but ask them to pass on their experience as well.
A satisfied customer tells 5 people; a dissatisfied one tells 20 people. If you ask him, I bet you can get a guy like this to tell 50 people simply because you exceeded his expectation!
This post may be received uncomfortably by you...I hope not; that's not my goal...but success is an outcome of active effort. The more active you are, the more outcome you get.
If you don't grow where you're planted, you'll never BLOOM - Will Rogers