[Tim Brewer]

It may or probably have been put in that way. You can't pump up a lifter and make the valve close the gap, valves and sparkplugs live side by side and it is impossible for them to touch. It is also impossible for a cam to cause any problem either. One thing that could cause a problem like this would be too tight of a piston/ head clearance. But if that were the case, you would have a problem with all your plugs. Also make sure you have the correct reach/length plug. But I think you have everything under control for now.
Good luck...
Tim