Why does my husband do this during sex?

If my husband still has his shirt on, he'll sometimes hold the bottom of the shirt out in front of him during doggy style.

Like, he'll grab the bottom seem with his thumbs and push it out up against the top of my butt. Maybe as if he's trying to block his view of everything or something?

I didn't have much experience before my husband, so I'm not sure if this is normal? I'm an overthinker, so of course I'm feeling self conscious about why he might be doing this and don't want to ask him.