Hi, My 16month Old Little Boy Fell About A Month

Hi, my 16month old little boy fell about a month ago at nursery, and banged his head. He seemed fine after a few mins of tears and cold compress. Had a cracking bump and bruise. Looked close to splitting as it didn't cut, but scabbed over in the days after so much have been close! Anyway, as I said he seemed/seems fine but there is still a lump there! Should I be concerned?