Does you post say your family is going out of town and when you're leaving?!
Forget the issue of friends responding. You have just let the world know your house will be empty, and when. I've seen too many news reports and articles saying that this kind of post is an invitation for burglars to come on by -- you won't be there. You have a house sitter coming- great. Does the house sitter know you've publicized the fact you're away?
And it sounds like your page isn't very limited as far as who sees it, if people you havent' seen since high school found it and responded. Please pull your post or alter it so it's not obvious you are leaving town. Though it may be too late; it's been up there for others to see.
Safety issue, security issue, and social issue too - this is why we don't do Facebook.