From everything I've heard and been told it's likely a flexibility issue unless you've got some previous injury or something along those lines.
I'm 42, prior injuries, I grip the bar pretty wide. Much wider than I see some others doing, wider than SS suggests... and not as wide as yet some others do it. And by "grip" I mean the bar is at the very bottom of my palm, little & ring finger kinda around the bar. I definitely get better upper back tightness with my grip closer, but also get shoulder pain that's significant enough to keep me from sleeping, elbow pain, both of which then impair other lifts. I found it easier to get used to a wide grip.