boyfriend 23m used to have crush on his friends,,,

my bf(m23) told me he used to have crush on three of his female friends at different timelines ofc, he says it was like a weeks crush and it didnt matter to him so he did not tell me
i was casually asking about this yesterday and he told me after asking a few times , but he says it doesnt matter, he has told me about few of his dates before where he asked the girls out but not this cause he said it was nothing and he didnt act on it ,
i feel uncomfortable with this fact and he is still in touch w them although its different countries now but they can always travel, one girl is more closer than the others,I told him it makes me uncomfortable but he said its the past he cant do anything now.

he told me this after 1.5 years of dating, should i be bothered or just leave this?
tldr : am i wrong ?