I'm amazed they've done anything, tbh. Its not anything outrageous or uncommon. Someone I lived with in halls was a massive stoner and he set off the fire alarm one evening. We could see several members of staff in his room when we were outside and he had several bags of weed on his desk plus papers, a grinder and a bong. All of which were there when he got back. Security would often see people doing it as well, all they'd say was go outside and if people already were they didn't bat an eyelid.
You'll get a warning about future conduct and maybe a fine for smoking in halls. Thats it.