Inconsistent, slight hesitation and "clunk"
I have a Phil Wood BB,with FSA SLK cranks; both of these are pretty new to me, having been installed by the LBS in the past couple months (about 1000 miles in dry conditions, no reason the BB should need servicing) . The bike is a Bianchi Via Nirone (aluminum frame w/carbon rear triangle).
I have a potential issue, in that, occasionally, when I start pedaling I feel a very slight hesitation (like something isn't engaged properly), there's a slight "clunk." Then everything works like it should. This doesn't happen often, maybe once or twice a ride. It never happens after a shift (just to say that it isn't a shifting problem, I think), but always when I resume pedaling after I had either stopped or coasted; this is the only variable, and it doesn't happen when I hit bumps or anything. It only happens once at a time, like a knuckle that pops and then works fine, and it doesn't cause me any trouble. Just worried it's a sign of some problem.
I took it to the LBS and asked them to check the tightness of the cranks, and described what's happening. It checked out ok, but they said to try to pinpoint when it happens better, since the only thing I can really say is "it goes clunk sometimes. infrequently, and pretty much unpredictably."
My old FSA Gossamer cranks (w/stock BB) used to come loose. That's why I thought the cranks were loose.
Anyone have any good suggestions for diagnosing this?