Am i being stupid or would you be upset too?

my boyfriend had this relationship when he was 16 with his neighbour, now hes 21, and this only lasted a short while and he was dumped for an older man, and i never really thought anything of it because it was so long ago, he told me they haven't spoken since but yesterday as we were driving up to his house it was snowy and slippy and he drove up and i said "that was your neighbour girl at the bottom i think shes stuck" even though there was every bloke on the street helping her get up. We went in the house and i was talking to him, he was obvs ignoring me and he just interrupted and said "should i help her?" and i was like "ok" i was upset by this as i was talking about something very important to me. He ran, i mean sprinted down and outside to help her, the other lads had helped her and he was just standing talking to her ( i was watching from the window) for a while and he came back in a while later. This upset me and he know it did, he did have a go at me for being upset saying its just in his nature to help people and stuff, but it really upset me! I know she meant something to him as he wrote a song about her i think when he was 16 judging by the colour of the paper now lol It aggravates me, it could happen again but when im not there, she could be stuck and he helps her, it drives me mad, am i being possessive and stupid or am i in the right to be upset? we've been together for a year n a half btw