Mine was always bad between 1st & 2nd before the car/oils etc had properly warmed up in the mornings, ...and was bad between 5th & 6th gear whether warm or not (even at mild rpm levels).
Had the gearbox oil changed & some Molyslip added and ever since it's been smooth as silk.
I suspect yours would benefit from the same. Link: http://www.h-dev.co.uk/product_info.php?cPath=78_169_293_1418&products_id=25501