People form scoliosis as they age, usually due to degenerative disease. I'm sure you've seen kids wearing a full brace around their trunk, or one that kind of looks like they are leaning. I think it's 10deg off midline from the center. WAY more people have it than you think. That said, if you had your weight shifted to one side or hip wasn't perfect aligned it could show scoliosis as well.
I also do not work out with people that make me laugh, my wife, etc. I usually listen to music so I don't have many distractions. I made the same mistake as you, a buddy made me laugh benching. I had probably 405 or 415 on and dropped it, luckily had not put the clamps on and ditched the weights. My buddy was too shocked to even help. My chest hurt so bad that I went to the ER, had positive cardiac enzymes (like I was having an MI), but just took it easy for awhile. As I've found out lately, you can take a lot more abuse at 18 than you can now.
I've hurt my back like that deadlifting before. I always wear a belt now. Felt like someone gave me a stinger next to my spine for a week. It went away. I tore my labrum and one head of my bicep a few months ago. I am putting off surgery until after hunting season and college football (already paid for the lease and LSU season tickets) and have been taking it super easy. I actually am in better shape now than before I hurt myself...just from changing up from heavy to light high rep stuff.