Is this standard against an unknown?

Is there an argument for overlimping PF?

Full Tilt Poker No-Limit Hold'em, $1 BB (9 handed) Hand History converter Courtesy of Poker coaching - Get an online poker lesson - texas holdem strategy for real poker

saw flop|saw showdown

Button ($52.70)
SB ($16.70)
BB ($100)
UTG ($32)
UTG+1 ($114.85)
MP1 ($106.30)
Hero ($112.25)
MP3 ($43.50)
CO ($51.85)

Preflop: Hero is MP2 with , .
UTG calls $1, 1 fold, MP1 calls $1, Hero raises to $6, 4 folds, BB calls $5, UTG calls $5, MP1 calls $5.

Flop: ($24.50) , , (4 players)
BB checks, UTG checks, MP1 bets $24, Hero folds, BB folds, UTG folds.

Final Pot: $48.50