5 speed problem. Help.

[Notch 8022]

I have owned my mustang for only a couple of months and was told the clutch was replaced. I recently was driving the car and could not get it to move out from fouth gear. I pushed in the clutch and shut the car off. I then started it from a stop in fourth and onced I got some speed going the shifter became free again. I am not having any grinding problems What could this be?