Too emotional ??

Today while I was finishing laundry, my almost 4 year old found something on the ground. I saw it was a piece of dirty styrofoam. Without thinking I just told him ‘throw it out it’s dirty’. He got so upset at me and out of nowhere screamed ‘YOURE FAT’ … in my head I told myself.. ‘did this kid really called me fat??’ I didn’t mention anything and insisted him to throw away what he had found. I started thinking where did he hear this?? At daycare? It’s his first year in daycare. He is pretty big for his age weighting at 57lbs. I started to imagine other kids telling him he’s fat and it completely broke my heart. I talked to my hubby about it and he said they’re just kids.. if my kid didn’t seem to be bothered about it, to not worry about. Im currently 10 weeks pregnant and everything is just way too emotional right now. When it comes to this I don’t think I am exaggerating. I don’t want my kid to come home one day and tell me he doesn’t want to go to daycare or school because of this. … should I give this too much importance or just let slide??