True but you still had the same problem since the track pitch was also scaled down requiring finer absolute indenting accuracy of the head stepper drive. They got around this by including a suitable length of the base material used by the floppy disks themselves as part of the head carriage assembly which meant the changes due to humidity levels were cancelled out.
Obviously, putting a floppy disk in the drive that had been stored in a location with a different humdity level to that of the drive could throw this temporarily out of alignment but this was rare on account the disks were usually stored in the same room as the computer.