I think my Grandpa got my weed by mistake and smoked it?

I know it sounds funny, but it isnt. I was over my grandpas earlier and i was out on the deck smoking the rest of a blunt i had with my friends on friday(i only smoke with my friends and when they supply it, im not a pothead i never smoke alone really only sometimes). and my grandfather is a cigar smoker and the blunt looked just like the cigars he smokes. after he was done he came in and said he felt "light headed" and his eyes looked slanted... my father was going to call an ambulance, and my grandfather said he was just tired. so we stayed for a few extra hours to make sure he was ok. i didnt tell my dad cuz i didnt wanna get in trouble, but i will if my grandfather could die or someting he is almost 80 and lives by himself. plz tell me thnk you