Unlocked plus padlock on reboot screen
So I recently put a micro SD card in my phone from my old S3. The phone worked for a bit then all of a sudden froze up. I had to take out the battery to restart the phone and when the phone came to the reboot screen it said "unlocked" with a unlocked padlock.
I did some searching and found that other people had the same thing happen with their phone after unlocking or flashing new ROM. The thing is I have never attempted to flash a rom or unlock my S5... ever. I literally got my phone the day it was released at ATT so it cant be a refurb that was unlocked or something previously.
I took out the SD card and rebooted and the unlock screen went away. The SD card had some filed and older pics and videos from my old S3. Im lost... any ideas?