Thunder AVS clogged with debris

Has anyone had problems with a new carb being affected by particulate matter? Took the dart to get the wheels balanced, and halfway there I think my car is running funny. When I get there, I stand behind the exhaust and listen and it sounds like a 4 cylinder John Deere! Go home check the wires cause I have new ones in the basement. On go the Taylor wires, no difference. Now Im wondering bad lifter maybe,- it happened too quick for a cam lobe, what gives? Off to my mechanic who swears its the new 650 avs. So I trust him and he has his carb guy buy a rebuild kit and take it apart. Turns out he was right, runs better than before, I can hear the cam again. No more tractor music. Should a new carb have machining/manufacturing debris in it that was big enough to mess with the idle circuit, or did I get a one in a million carb?