It is impossible to say without knowing what your normal levels are, and what you were after the previous meal you had at 11am
If you see an unexpected number, it is best to do a re-test straight away as we all get rogue readings from time to time - and either one of those readings could have been a rogue one. Did you wash your hands thoroughly and make sure they were dry?
Having said all that, if 13mmol/l was accurate enough, that reading was high. Double figures are never a good idea.
What did you eat at 11am?