Urine test normal urine culture positive

My 3.5 month old son had an episode of uti when he was 13 days old, treated in nicu and since then on Sporidex, which needs to be continued till 6 months of age as advised by pediatric surgeon. As we would be traveling, just for routine purpose, we got his routine urine test and urine culture done. His urine test reports came totally normal. But his urine culture showed growth of Morganella morgenii. He's totally normal and active, and doesn't show any signs of uti. He's feeding well and pee count and weight gain is also proper. So looking at all these, his pediatric surgeon has told us to not to do anything now, and keep continuing Sporidex. As there is no fever or any other signs, as well as routine urine test is also normal, we can ignore the culture report. Is this normal that urine routine is fine but culture is positive?