Lots of things cause this, and unless you start to see a pattern, it could just be an anomaly. You may be getting over your honeymoon period too. So these are to be expected.
Could be excitement, stress, change in weather, absorption. You could have just done a dodgy injection so it didn't absorb properly for your lunch.
Generally I have been taught not to correct unless I'm over 12 (it's normally 10 but I'm so sensitive to insulin) unless it's with a meal.
So keep an eye. If you find you usually go higher this time, your needs may have changed.
Just another point, you'll find your insulin needs will change quite a bit. Different time of year, different time in your life. That's why pattern recognition is so important.
All the best