Something might be loose, that's my guess. If it's really noticeable then I'd send it back but again that's just me.I had the same problem it is very annoying it only registered the new battery percentage when you shut the device of then back on. Mine actually started flickering and froze black and wouldn't come on so I called Google and they sent me a replacement. My replacement has a squeaky back like it's not solid, contemplating on sending this on back also..
lol Third time's the charm hopefully.Yeah I think I'm going to. When I talked to google they said to inspect the new one and make sure it's good so, it's not good lol