This was a deliberate change some time last year. Another user complained that the last played wasn't updated if they watched 90% of a movie but stopped at the credits, so it was changed so that last played was updated 5 minutes after starting playback.

Personally I preferred it when last played was only updated on completion.

Then I can reproduce: http://www.ventismedia.com/mantis/view.php?id=14162

For me it was Last Played Date, but I'll test more thoroughly when I have access to my Windows machine tonight.

Do you mean the Played#? It didn't change here on a long pause.

When pausing a track for a long time, it gets marked as played regardless of whether it is currently playing or paused. This means that I can pause a track immediately after playback start and it will eventually get marked as played even though I haven't really listened to the track.

MMW 4.1.16.1831