Folded full house?

I'm going daft about this hand. it was the end to a big losing session for a strugging microstakes player recently getting back to the grind. any thoughts would be great. MP had a vpip of 23, 3bet of 20, 1.6 agression factor and 3bet of 14,

PokerStars - $0.05 NL FAST (6 max) - Holdem - 6 players
Hand converted by Holdem Manager 3 : http://www.holdemmanager.com

BTN: $10.03 (200.6 bb)
SB: $6.06 (121.2 bb)
BB: $5.12 (102.4 bb)
Hero (UTG): $19.56 (391.2 bb)
MP: $16.56 (331.2 bb)
CO: $1.74 (34.8 bb)

SB posts $0.02, BB posts $0.05

Pre Flop: (pot: $0.07) Hero has 3c 3s
Hero raises to $0.12, MP raises to $0.36, fold, BTN calls $0.36, 2 folds, Hero calls $0.24

Flop: ($1.15, 3 players) 3d 8s 8c
Hero checks, MP bets $0.54, fold, Hero calls $0.54

Turn: ($2.23, 2 players) 9s
Hero checks, MP bets $0.71, Hero raises to $1.96, MP calls $1.25

River: ($6.15, 2 players) Kd
Hero bets $2.95, MP raises to $13.70 and is all-in, Hero folds

Results: $12.05 pot ($0.50 rake)
Final Board: 3d 8s 8c 9s Kd

MP wins $11.55