Why is there a serial number in my new lcd display?

I have just received my new lcd display that I have recently order from ifixit last month (11/25/014)for my ipad mini, the repair went smoothly with just a few minor set back. After the installation

repairs, I turn on the unit, it power up the apple logo appears, no problems whatsoever. But I notice something. Half way down in the right side of the display, there appears a four digits, numbers 4904T. Thinking that I probably forgot to remove a protective sheet

from the display, remove the digitizer and check for the protective

sheet, but did not find any on the display. I have also check

the digitizer glass, but found nothing. Just to be sure, l turn on the

ipad without the digitizer glass, and chech the lcd display, the numbers are still showing on the screen. I have also open other

programs, like safari, apps, utilities, youtube and games, with the same results the numbers are still showing. Is this normal for a new lcd, if not how could I resovle this issue. Thanks.