Have you ever checked before your normal time(wake up a hour sooner?) and then check 1 hour later to see what is happening? For me testing I can get 4.8 or even lower depending where I am in the cycle. I've also noticed repeat testing makes my numbers go up very quickly.
I used to test on different devices, and left me wondering why accu-chek mobile was lower. I then tested on the accu-chek mobile last and got worryingly higher readings, so I only use one, and test once, job done. With me I get more stressed in the mornings with even my hand shaking when trying to check my fasting, so I don't bother when I feel stressed these days, as it jumps up quicker than I can test, and doesn't do anyone any good seeing false higher readings even if it's still in range, it leaves me with a headache.
Today fasting I got: 4.9mmol/l, did not test breakfast as I've tested that this twice this week, and is keeping in the 5s so no point as I eat the same thing, after lunch: 5.5mmol/l(55g carb meal) but that will be it for a week or more, as I can see anything is still fine, and too much testing stresses the hell out of me out these days and ends up giving me higher readings.