Yep, totally normal! At 4 months, ang babies usually sleep longer stretches at night na, so pwede ng all-night diaper, lalo na kung mixed fed siya, mas mabigat ang feeding so longer intervals between poos. A few of us sa circle namin, ganyan din ang babies namin around that age, especially kapag gabi na. Just check na hindi siya overwhelmed o uncomfortable sa wetness, at monitor kung may diaper rash, pero mostly, you're doing great! If you're ever worried about anything unusual sa health side, always okay to check with your pedia lang para peace of mind.