Did I get bluffed here?

GG Poker - $0.25 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

BTN: 83.88 BB
SB: 101.4 BB
BB: 100 BB
Hero (UTG): 101 BB
MP: 101.4 BB
CO: 100 BB

SB posts SB 0.4 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.4 BB) Hero has K♥ K♣

Hero raises to 2 BB, fold, fold, BTN calls 2 BB, fold, BB calls 1 BB

Flop: (6.4 BB, 3 players) 7♠ 7♣ 5♠
BB checks, Hero bets 2.24 BB, BTN calls 2.24 BB, BB calls 2.24 BB

Turn: (13.12 BB, 3 players) 8♠
BB checks, Hero checks, BTN checks

River: (13.12 BB, 3 players) 7♥
BB checks, Hero bets 23.6 BB, fold, BB raises to 95.76 BB and is all-in, fold

Hero shows K♥ K♣ (Full House, Sevens full of Kings)

BB shows 5♦ 7♦ (Four of a Kind, Sevens)

BB wins 55.92 BB
During game, he only showed me the 5 of Diamond. I've been noticing that if your villain only show you one of their hole cards on river, the PT4 somehow records both of their cards. Just so you know, if you don't want your opponent to know what you had, don't show any of the two hole cards because all is revealed if you just show one card.