When a stock VZW SG3 boots, a white samsung bootlogo is displayed. If the firmware of the phone is modified, an additional bootlogo reading "custom" and showing a lock in the unlocked positon may appear. On my phone I can induce this by deleting a few .png files out of SystemUI.apk. Another user here (DebianDog) noticed this first when he followed my lead in deleting the GPS location services icon (Q: How do I remove GPS icon from notification bar?).
If I replace those APK files with stock ones, I cannot get this additonal "custom" bootlogo to dissapear. I have rebooted many times and the "custom" boot logo persists. However, if I restore my stock nandroid, then the custom boot logo is absent and it only says "samsung." I repeated this several times to confirm this. See the image below for an example: