If You Are Grappled wrote:
If you are grappled, you can attempt to break the grapple as a standard action by making a combat maneuver check (DC equal to your opponent's CMD; this does not provoke an attack of opportunity) or Escape Artist check (with a DC equal to your opponent's CMD). If you succeed, you break the grapple and can act normally. Alternatively, if you succeed, you can become the grappler, grappling the other creature (meaning that the other creature cannot freely release the grapple without making a combat maneuver check, while you can). Instead of attempting to break or reverse the grapple, you can take any action that doesn't require two hands to perform, such as cast a spell or make an attack or full attack with a light or one-handed weapon against any creature within your reach, including the creature that is grappling you. See the grappled condition for additional details. If you are pinned, your actions are very limited. See the pinned condition in Conditions for additional details.
The penalty for not having 2 hands free is only to start a grapple (inferred from the paragraph starting with "As a standard action, you can attempt to grapple a foe," and later "If successful, both you and the target gain the grappled condition.")
If this were not the case, the grappler would also take this penalty on all subsequent rounds unless he possessed one of the abilities that prevents you from gaining the grappled condition.
The paragraph I quoted mentions nothing about needing to take a penalty other than the Grappled condition.
