First there is a difference between defensive behavior and aggressive behaviour, BP are not know for aggression but they will get defensive.

Usually this behavior is link to stress which can be due to frequent handling, husbandry issues (lack of security), feeding issues .

Live feeding does not create this behavior neither does feeding in the enclosure.

Stop handling your BP, make sure you feed the right amount of food, double check your husbandry (temps, hides, enclosure size etc).

Even if the animal has been in the same setup for months it does not mean it is the right setup for your animal and stress can build up over time.

So not with all that in mind time for YOU to see what triggers this.