Aww, what a great Momma you are.
No, you're not overreacting at all, it is tough on you and your Yorkie if you are not with them for a long period of time. He will be fine, as you do trust your parents with Mr. Pink. We usually take a few pictures of Yoda with us and prop it up in our hotel room and we always acknowledge him as if he was there, like say "Good morning" and "Good night Yoda!". We also called Yoda too and said a few words to him on the phone.
He's always soooooooooo happy when we get back!