Am i hearing things? saying something?

My baby is 3 months old. This is gonna sound crazy but for the last week it sounds like he's saying mom when he cries... i went to visit family and they would laugh because it sounded so much like he was saying mom but i just thought it was him practicing sounds and what just came out when he cries but today he looked right at me and said mmmmmoooommmmm like it was a struggle but calculated and on purpose is it all wishful thinking or do other moms hear their babies practicing sounds like that or could he have said it. He can roll all over my living room and scoot and get up on his knees is all that what he should be doing at his age or is he behind in some of that stuff he started rolling over front ways and back ways last month