If after the preacher said he fixed the problem you said "That may be, but we still appear to have a problem." he may not have reacted the way you said. Some people in some situations get defensive very easily and then it's tough to get back to cordial communications.
Being too direct (in the interests of efficiency, of course) triggers these defensive reactions. So saying things like "I could be wrong, but...", or "Help me understand why..." and other such mealy-mouthed expressions which cannot be taken as accusatory. One of the hallmarks of a good working relations with a coworker is that you can dispense with these expressions.
So practice such mealy-mouthed talk! :)