I get that too but not pretty often. Usually after reversing and the going to 1st I get a grind and thats it. I remember when I had my stock shifter it happened once. So now with the short shifter I guess the chances have increased.
Its not a big problem for me..it only happens like once a month. If it happens frequently on you you should put back the stock shifter and see if it goes away. If it doesnt then you know its the tranny.