Piston question

I checked my ring gap today and I'm way off on the top ring I'm getting like .019 so is it ok to file fit a non file ring set? The rings that came with my pistons are listed as non file. Is it ok to go ahead and file them or do I need to order a file fit set?

I've always done it with no ill effects but I'm sure somebody will be along to tell me how stupid I am. My question is why didn't you get file fit to start with?