I doubt it was Salvia. You don't smoke that the same way you smoke weed. You have to hold it in for a long time, like 10-20 seconds to get the effects. Maybe if it was a high extract, but then I'm sure the weed would taste different. Not to mention that he said the weed is fine now, and that he had smoked some before he had his freak out.

My hypothesis: Your weed isn't laced. It's good weed, and you either got a really good hit that time, or there was another problem such as blood sugar or blood pressure. If it happens again you need to see a doctor.