My hurst shifter used to do this on shifts from 1st to 2nd on occasion. I had to go under the car and push one of the shift rods forward before it would release. It turned out that the inside of the shifter was so gummed up with dirt and gook that sometimes both shift rods would move at the same time when only one was supposed to. Of course the fix was to take the shifter completely apart and clean and relube it. No problem since.