Im pretty sure i am on t vert they are selling air too keep the prices down and covering on t trades so they dont show up on the l2 on the bid...jmho.
That last trade of the day looked more like someone wanting in before the close of trading and before the weekend. If you look at the trade, you will see it actually started going through prior to the close. IMO, the order did not fill completely until after 4PM, thus showing up as a T-trade.
I wonder if it was more someone keep that ask-sitting stock-blocker honest. Ever play poker? Thats why I'm curious to see how Monday's trading begins...more so that usual. Keep an eye on the bid--side for 'strange activity'.