Upshift Switch Circuit Problem

Hello the other day i was at walmart and shifted my car into reverse and the CEL came on. Along with this the D light started to blink. There was snow outside but not too high. I went to advance auto parts and they pulled up the engine code P0815 Upshift Switch Circuit. As I was driving home everything felt fine, and shifts were smooth.

I googled for a fix but I haven't gotten any clear answers.

Does this mean my transmission is slowly breaking down on me and I need a rebuild soon?

Any and all help is appreciated, thank you guys in advance