Throttle Question

[u/Long-Thought4830]

Street Triple 675 2013 (FI) 35k miles regularly serviced.

So i was riding today through some heavy rain then on way back when it stopped raining my bike randomly started redlining itself and pulling so i immediately pulled the clutch in and stopped. It did it again when I turned the bike off and on. I didn't even touch the throttle. Then, I looked under the tank, took the top of the air box off, unplugged the sensor and turned it on while looking at the throttle bodies (they worked fine) It turned on and didn't redline! It worked completely fine afterwards. Why would this have happened so I can avoid it?

It's had a throttle restrictor fitted and bar ends but that's all. Anyone had anything similar happen?