I haven't toked in about a month...but I've had the same stuff happen to me a few times. The times that this did happen was when I was worried about getting caught before I even started blazin. Then the bud just boosted my paranoia. But, the nice thing is is that if your havin a good time already, weed boosts those pleasant feelings. Thats how i see it anyways.
so....My advice for u is to first be with people that you would have fun with sober. And goto a place where you feel comfortable. THEN take a few tokes. And don't even think about it.