As other say, they are much better at picking up on body language as they are very signal orientated. So it has more than likely noticed that you are starting to break your routine.
I wouldn’t worry about it, other than making sure it has the same food when its away and ask you friends not to feed it anything too rich (including treats) as depending on the dogs history (especially if its a puppy farm dog) the nervousness + rich food can lead to stomach infections.
My second dog, can be a nightmare if she goes to kennels/away for the weekend, as it usually ends up with her shitting blood and a £200 vet’s visit and antibiotics due to her getting so nervous. Mind you she was dumped in the middle of know where when she was two due to her owners getting bored of her, so I can hardly blame her