Oh yes. Those nerves and antsy-ness? I still get it after a long T vacation (long as in 7+ days
which means missing 2-3 appointments for me) I also know that I tend to do one of two things on my first session back after a break. I either a) go in all nicey-nicey and have a very light session just chit-chatting and avoiding anything serious (and usually end up crying all the way home for not talking about what I really needed to talk about) or I b)intentionally try to piss T off cause I'm mad that she was gone.
Thankfully, T knows me quite well by now, and doesn't let either of those situations last long - if I'm all chatty, she'll let me go for about 10 minutes or so, then cut right to the chase and ask what I'm avoiding bringing up. If I'm pissy and trying to frustrate T, she'll let me rant for about 10 minutes and then again, cut to the chase and acknowledge that I'm likely avoiding my feelings about her being gone, which is true, and it gets me every time.
I guess what I'm trying to say (rather long-windedly) is that it IS pretty normal what you're experiencing! The important thing is to not cancel the appointment, and try to bring up what you're feeling right now so you can talk about it with T. From reading here on the forums, it seems like a lot of people (myself included) have ruptures once their T returns from a break. In talking about your feelings right now with T when T returns, it may help avoid a situation like that.
As for the stranger part, it took at least a half dozen breaks from T for me to realize that T ALWAYS comes back the same T she was when she left. I still get anxious that she'll be different when she returns, but I know that's just my fear talking, cause so far, she always comes back the same (though sometimes a little bit tanner!)