Unexplainable spikes….

After having been diagnosed for about a month, my numbers are trending down nicely….often double digits or low 100’s, except a little higher upon wake up.
Yesterday afternoon, before dinner, a time when I have regulary been testing in the 90’s, I tested @ 134. I did not have anything unusual or higher carb for lunch, and am curious as to why I would suddenly test higher for no reason.
2 hours after dinner I was down to 107.

Can anyone explain this unexplained spike? IS this common?