its evident that it may have been opened (not sure for what). but as mentioned above, if all works great, no issues at all, just use and enjoy it. other units have issues, and risky to get those to replace a perfectly good one (aside from that bump).
LG-D820 & ME571K on KOT49H
ST25i on Stock JellyBean 4.1.2 V6 lite
A1395 on iOS 7.0.4 | A1432 on iOS 7.0.2