When two previously passive players suddenly perk up when the 4th card to a straight hits the river, even a beginner like myself gets the hint...

Party Poker 0.15/0.30 Hold'em (9 handed)

Preflop: Hero is Button with , .
1 fold, UTG+1 calls, MP1 calls, 1 fold, MP3 calls, CO calls, Hero calls, SB completes, BB checks.

Flop: (7 SB) , , (7 players)
SB checks, BB checks, UTG+1 checks, MP1 checks, MP3 checks, CO checks, Hero checks.

Turn: (3.50 BB) (7 players)
SB folds, BB checks, UTG+1 checks, MP1 checks, MP3 checks, CO checks, Hero bets, BB calls, UTG+1 folds, MP1 calls, MP3 calls, CO folds.

River: (7.50 BB) (4 players)
BB checks, MP1 bets, MP3 raises, Hero folds, BB folds, MP1 3-bets, MP3 calls.

Final Pot: 13.50 BB

Results in white below:
MP1 has Kc 7d (straight, eight high).
MP3 has Jh 7s (straight, eight high).
Outcome: MP1 wins 6.75 BB. MP3 wins 6.75 BB.

Or was I wrong to even play the suited connectors on the button to begin with?

Nah... 56s is fine for a 7 handed pot. Good fold.

Good fold. Given the table conditions, 65s is fine on the button.