UTG and wanted a caller or two. What was I scared of on the flop?

PokerStars No-Limit Hold'em, $0.10 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Hero ($5.90)
MP ($16.90)
CO ($10)
Button ($3.75)
SB ($25.75)
BB ($9.25)

Preflop: Hero is UTG with A, A. CO posts a blind of $0.15.
Hero raises to $0.4, 2 folds, Button calls $0.40, SB calls $0.35, BB calls $0.30.

Flop: ($1.75) 3, 2, 3 (4 players)
SB bets $1.25, BB calls $1.25, Hero raises to $2.5, Button raises to $3.35, SB folds, BB calls $2.10, Hero calls $0.85.

Turn: ($13.05) 5 (3 players)
BB checks, Hero bets $2.15 (All-In), BB calls $2.15.

River: ($17.35) 9 (3 players, 1 all-in)

Final Pot: $17.35