Can someone confirm if the film has been tested with a densitometer?

I had some 400 speed HP5+ that I took overseas, someone in my camera club has a densitometer and he said the film has more fog than normal. Not sure if this was b/c I had film that was some yrs old or if it was xray related however you can still get nice prints off them. Off the same person he showed a person about fog when you use the fixer too many times but still adhering to Ilfrord's recommendation. He now uses 1L of working solution of fix for 6 rolls.