Baby finger sucking?

My little man found his fingers about a month ago and I’ve noticed lately that he’s been putting them in his mouth a lot. Sometimes it’s because he’s hungry, but my concern is that he’s stressed in his environment and needs to soothe. I’ve never met him cry it out, In fact he barely cries at all, our house is usually really calm. His dad and I argue occasionally but nothing crazy just a bunch of bickering because being a new parent is stressful and tough on your relationship ya know. Am I doing harm to my baby? I’m so concerned that he’s doing it because he’s not having his needs met or his environment is too much. Please help