small circle from logic board fell off, anyone have this happen?

hi guys, before i start, i just want to say that i have replaced about 40 iphone 4 and iphone 5 screens so i would say that i have a medium amount of experience in this so here goes.

i was taking apart an iphone 4 AT&T today and i was un screwing the screws at the top flex cable cover and where one of the screws were under the cover a small round piece that the screw screws into came off of the logic board

at first glance i tought it was just a washer, but when i looked closer it looked like the small round piece was soldered on.

i went ahead and replaced the screen but when i put the phone back to gether it would not come one. i re took the phone apart 2 more times and put it back together and the same thing.

this small round piece broke off of the logic board and i just dont know if this is the cause of it not booting up now.

i am going to show some pictures of where the circle piece came off of

http://i.imgur.com/yC2XRuG.jpg

this picture shows where the circle piece was before it came off when i un screwed the screw from the flex cable cover.

it was right under that sort of metal hook on the logic board

http://i.imgur.com/BnPg4BG.jpg

and this is the picture of the actual piece that came off.

i am just asking if anyone else had this problem when they un screwed that one screw on the flex cover and that small round piece came off of the logic board.

if anyone has had a similar problem and found a solution, please let me know. thanks guys