Player A is UTG
Player B is in CO

Pre-Flop

Player A limps, folds, Player B raises to 4x BB, folds, Player A calls.

Flop



Player A checks, Player B bets 2/3 pot, Player A min-raises, Player B calls.

Turn



Player A checks - What is this a sign of?

Assume neither player is an extreme LAG or TAG and 100BB stacks.