I would say on any "interior" pieces.... it isn't a big deal. You'll "close in" those seams with new seams and your piece will be stable.
But if you have any large pieces on the outside edge of your block, you should try to keep straight of grain on those. If you have exposed bias on the outside edges of your block, be extra careful removing the paper. Also, your block will be susceptible to all the regular problems exposed bias has on the OUTSIDE edge of the block.
Do remember to use a much shorter, tighter stitch length for paper piecing to make removing the paper an easier task. Also, remember that on the OUTSIDE edges of your block, you can sew into the seam allowance. Only on the INTERIOR pieces do you need to start and stop precisely on the lines and intersections.
Kathryn Groves