Why should i quit wearing low cut tops in front of my son?

I am married and have one son who is 13 years old, a few days back when we wear going out, i had worn a low cut salwar khameez. I such clothes most of the time, my family does bother about it .A few days before when we wear going out , i had bent to put on my sandals, and i think i showed a bit of a cleavage and i think my son was watching it.My husband quickly went and lowered my dupatta(i usually wear the dupatta just around my neck) and he told to be careful next time. is there anything wrong.