I've had a weird thing happen to me twice while driving my car. Basically motoring along rowing through the gears and when I put the car in gear and release the clutch it sounds like gravel being thrown around in the transmission. Both times it happened I pushed the clutch in pulled it out of gear put it back in gear and released the clutch and the issue went away and never appeared again. This isn't like grinding gears trying to find the gears this happens when the car is in gear. I know my throw out bearing is shot because I'm getting the blow off valve noises when I shift and the fluid I'm using doesn't like shifting into 2nd when cold but I think those are separate issues and wouldn't cause this sound, correct? Another data point this has happened once in 2nd gear and once in 5th gear so not gear specific. Any ideas?