I have a Nokia Lumia 920 with the latest WhatsApp application. Sometimes it happens that my last seen is wrong.
For example, once a friend of mine checked my last seen at 20:10 on his phone, and WhatsApp reported that my last access was @ 20:08. I am sure it cannot be possible because I was next to him, talking.
I am sure that there are no web browsers logged in my whatsapp, too.
What could it be?