Wanted to know if anyone else has experienced something similar so I know what to look for.

I was going fast on the highway on high revs in 4th gear when I shifted to 5th it was very grindy and did not go into gear, so I went back to fourth with a rev match then back into 5th fine. Getting off the highway I noticed smoke coming from the back of my car, it would smoke then stop off and on until I got to a stop. Smoke was coming from under the car after cooling it down I smelled burnt gear oil which I assume was from the transmission. The fluid was smoking after hitting my exhaust. There was no difference in drivability nor was it constantly leaking from any spot while parked. I could not pinpoint where the fluid had come from due to the wind blowing it everywhere.

I have driven it very little since with no difference in feeling but I feel uncomfortable taking it anywhere further until I pull the transmission tommorrow. Any ideas what this could be its not the rear seal and by visually inspecting it under the car I cannot spot anything on the transmission either.