Docile BP struck. Any help?

So, I have had this little guy home for a week.... He ate 5 days after I got him home... I let him digest for 48 hours and took him out today. He's 9 months old and was very docile at the reptile shop(visited him 3 times before purchasing). He is a normal morph and has been great while holding. Today, I put him on the carpet floor to explore and my 7 year old who absolutely loves snakes was sitting on her knees on the floor and he all of a sudden struck towards her and I could tell he was tracking. I picked him up and held him close and let him calm down for a minute and placed him back in his enclosure. Do you think maybe we had him out for too long, should we not let him crawl around yet? Was he stressed bc it was daytime and he felt defensive, or a combo of all of the above? He didn't bite her but definitely struck, mouth open and has not struck before. He was one of the snake's that the shop allowed to be held. Thanks in advance for any words of wisdom, as I am a new BP owner and I am loving it!

I try not to handle new arrivals until they've eaten at least 3 times. He's still settling in and it may have just been too much going on around him. I probably wouldn't have him around young kids just yet.

Totally NORMAL & predictable. Snakes don't see well...we are SCARY to them, once we aren't close enough or touching them so they recognize us. He was scared, &
only acting on instinct: a large creature (aka human) towering over a snake on the ground (who is suddenly feeling SUPER VULNERABLE) is very likely to get a defensive
strike or bite...now you know. Prevention is the key...forethought on your part, so your little one doesn't have a bad experience. I've lived with snakes of all kinds for
many years...nearly all of them react this way when put on the ground, either indoors or outside. Your snake is STILL docile...it was your mistake, not the snake's. ;)

Thank you!

Thank you so much guys. He is such a sweetheart and her dream is to become a BP breeder with her own YouTube channel. I will make sure to limit his time out after he hets a couple more feeds in and go a little slower. ❤️