Agressive Villian / blocking bet on river

[aggie]

Villian seems VERY aggressive although i have very few hands with him. I'm curious what y'all think of the blocking bet on the end? Does it scream weakness?

PokerStars No-Limit Hold'em, $2 BB (5 handed) FTR converter on zerodivide.cx

Button ($403.75)
Hero ($290.30)
BB ($266.35)
UTG ($343.70)
MP ($150.35)

Preflop: Hero is SB with A[img]/images/graemlins/club.gif[/img], J[img]/images/graemlins/club.gif[/img].
<font color="#CC3333">UTG raises to $6</font>, <font color="#666666">2 folds</font>, Hero calls $5, BB calls $4.

Flop: ($18) T[img]/images/graemlins/club.gif[/img], 7[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets $15</font>, <font color="#CC3333">BB raises to $30</font>, UTG folds, Hero calls $15.

Turn: ($78) A[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, <font color="#CC3333">BB bets $40</font>, Hero calls $40.


River: ($158) 3[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $50</font>, <font color="#CC3333">BB raises to $190.35</font>, Hero folds.

Final Pot: $398.35