breastfed babies poop?

My baby is a little over 4 months old, his pediatrician said I should start cereal, So I've been letting him have some, he loves it. He pooped just a few minutes ago and there were decent sized clumps of poop in his diaper, still soft and most of it was still kind of runny but he's never had clumps and I'm wondering if its from the cereal? is it bad?