It's worth asking. Offer to give them contact info for people you'll be with; that's what I had to do with my parents the first time I went out to meet somebody from the internet (in this case joecam); my parents called joecam and talked to him, and after comming to the conclusion that he wasn't a rapist and ax-murderer, they let me go to meet him, and they've had no problem with me going to meet people from the internet ever since.
Can't speak for anybody else, but you can give them my contact info if need be.