Today on my forum I had a conversation with a member. When viewing the member profile it says: "Someone was last seen: Today, 13:51"
However this member replied to the conversation at 13:54, then seconds later he left another message on the same conversation at 13:54 too and finally at 13:56 he left another message. So his last activity was at 13:56.
What could be happening? The time on my server seems to be ok with synchronization up and running (ntp).