Stars $400nl My river value bet gets c/red

[myke11]

Villian is unknown to me, he had just sat down and I didnt even have stats on him.

Poker Stars, $2/$4 NL Hold'em Cash Game, 6 Players
LeggoPoker.com - Hand History Converter

BB: $336.50
UTG: $91.05
Hero (MP): $414.50
CO: $787.90
BTN: $741.70
SB: $585.75

Pre-Flop: A[img]/images/graemlins/diamond.gif[/img] J[img]/images/graemlins/diamond.gif[/img] dealt to Hero (MP)
UTG calls $4, <font color="red">Hero raises to $16</font>, 2 folds, SB calls $14, BB folds, UTG calls $12

Flop: ($52) 4[img]/images/graemlins/diamond.gif[/img] A[img]/images/graemlins/spade.gif[/img] 6[img]/images/graemlins/club.gif[/img] (3 Players)
SB checks, UTG checks, <font color="red">Hero bets $38</font>, SB calls $38, UTG folds

Turn: ($128) 4[img]/images/graemlins/heart.gif[/img] (2 Players)
SB checks, Hero checks

River: ($128) 2[img]/images/graemlins/diamond.gif[/img] (2 Players)
SB checks, <font color="red">Hero bets $100</font>, <font color="red">SB raises to $420</font>, Hero folds

Results: $328 Pot ($3 Rake)
SB mucked and WON $325 (+$171 NET)

I feel like with my pot control line my hand is pretty face up, so a good player could bluff here. However, vs an unknown is this hand standard?