could the passcode change when screen is replaced?

Hello

i replaced a screen for my friend , and when i gave it to him it was working perfectly , i told him to check for mic , speaker , front and back cam , and he did that all infront of me and it was all fine

after that he was gone for 10 minutes , and thencame back and told me that when he tried to enter the passcode , the phone showed that the passcode is incorrect

i tried the screen and it was working fine , it didn't press anything outside touch area

and then to convince him i returned the old screen, it was also working fine and he could enter the passcode correctly but the glass was damaged , and the phone also showed that the passcode was incorrect

i told him that he must have changed the code when he was gone , but he said he didn't

so what happened ? is he lying or did i do something wrong ?

thank you