There are so many potentials for what happened, it's impossible to go into them all. But for examples:
-Maybe the particular carbs weren't the best for you
-You were just starting a liver dump as you tested "before" and therefore didn't record it, then ate "on top of it"
-You were a bit stressed between the tests
-You were more sedentary than usual in the 2 hour period
-You miscalculated the carb count
-Either test was "inaccurate", by virtue of all the usual factors; contaminated finger, meter variances, contaminated strip
So, it's best if you repeat the test at least another once (better twice) for further clarification.
Good luck with it!