Can you snap a quick pic of the gap? I just watched the 3 Youtube reviews posted previously and didn't see a gap although he didn't focus on the sides of the phone. If you have a store nearby with a P5 on display I'd head over there and compare and send it to Google if they try to blow you off.
The specialist has said it's not right. Offered a replacement, then offered an advanced replacement.
Not sure whether to do it, or just return for a full refund.