NismoKAGE

i recently swapped a s14 blacktop in my 89' s13, i recently drove it from las vegas to pullman washington, trip took three days due to the ice and snow, it gave me NO problems. i changed the oil and spark plugs, but not the filter because i couldn't reach it so ima do another oil change in a month. i ran my car up and down the street kinda hard two or three times and when i stopped i couldnt shift to save my life, as if i wasn't pushing the clutch down. i forced it in reverse and parked and turned everything off and waited five minutes, turned it on and it shifted like new, im thinkin it has something to do with my clutch or slave line since i replaced it with the swap, wat could it be? thanks