Q: Possible transmission issues

The other day my girlfriend was driving the car, the engine was reaching 4,000 - 5,000 RPM before shifting into even 2nd gear, the check engine light came on, and another indicator light (red lighting bolt) came on, the manual said the other indicator light had something to do with the throttle, but that light turned off almost immediately, the check engine light however, stayed on for about another hour or two, neither light is on anymore, but the car still reachs 4,000 - 5,000 RPM before shifting, it doesn't sound like the car is struggling or anything but this wasn't happening before so it's a little concerning, also, a side note, the engine only reaches RPM that high when getting to 2nd gear, no other gear, everything else works fine, it down shifts properly and doesn't slip or jump forward, hopefully all this helps.

My car has 36000 miles.
My car has an automatic transmission.