Stringer/ string tension question

[Jpin76]

Before I start, I have a gamma progression II 602 string machine and I was stringing a head youtek IG radical pro with head rip control 17 string.

I set the reference tension on machine to 57 lbs and a measured tension using racquet tune. Why did my tension come in at 60 lbs when I measured?

I've strung a few times before and the tension when I measure usually comes in 5-7lbs below my reference tension. I'm just wondering what would cuz the tension to be above my reference tension on my machine.

I apologize if this question has come up before but I did a search and could not find any info......