Pics of girls from prior dates

My boyfriend of four months was showing me pics on his phone of his family but as he scrolled through, I could see a lot of pics of other girls. Just like a normal face profile pic, not anything more. But he then said oh those are pics of girls I dated before from a dating app. I said you could delete them? Which he did not really respond to. Seems odd to me to keep all these pics. But am I being too sensitive? Update: first thanks for all the support from you all! Second…. He deleted the pics! very happy