Today I was driving down the freeway and as I went to change lanes to pass, I noticed my 2008 Jeep Wrangler JK was running at 5000 RPM. I reached down and pushed the O/D button on and off and nothing changed. as I came up to a stoplight I shifted into park and back to drive. It didn't shift as smooth as normal, but did shift. Hoping that I don't have a major transmission problem, what could it be?