X-Carriage with smaller distance between bearings

After printing some X motor holders/ idlers and carriages (in this case what holds the bearings), I have found that the distance between bearings never matches exactly. I’m guessing it is because the parts are being printed in different orientations (vertically for the holder/idler and horizontally for the carriage).

The distance difference is really small, about 0.3mm, but it is surprisingly enough for the carriage to force the smooth rods apart and make the x movement not smooth, but forced