An industry source has told DigiTimes, "LGD was forced to reduce its shipments in the first quarter due to light leakage problem for panels produced at its 6G production lines." Because of these faulty displays, Apple shifted orders from LG to Samsung in the first quarter of this year. The shift pushed Samsung to 4 million iPad panel shipments, becoming the number one supplier for Apple. LG slipped to 3.2 million panel shipments in Q1 2011.
The source also told DigiTimes that the issue with the LG panels has been fixed and that LG would "resume shipment momentum to Apple in the second quarter."
source: DigiTimes via Engadget