My younger sister (who is now 26 yrs. old) has a sever peanut allergy as well.  She never eat peanuts (peanut butter) growing up, she just refused it.  Then when he was 5 yrs. old she touch a peanut butter sandwich and had a reaction.  It was then when she was diagnosed with a sever peanut allergy.  As she was growing up she always had to be careful, checking food labels and asking restaurant.   She was always very careful.  

About a year ago she was out for dinner with my other sister and of course like always she asked if there was any peanut products being used and the restaurant said no.  So, they had gotten there salad and after the second bit she started feeling weird and next thing you know she couldn't breath and my sister had to give her the epipen and the ambulance was on the way. It was very scary! She was treated in the hospital and was released the next night. 

Up until then she was unsure if she still had the allergy, she though maybe she had outgrown it but unfortunately she had to learn the hard way.

Good luck and be careful!