It depends of your relation with the horse... Horses have a very good memory so he can absolutely remember you! Unless he saw you only a few times.
Amy is right, we cannot really answer if we do not know more about your relation with this horse! If you had a strong and special relation with him, of course he can recognize you! But if he saw you twice a month for 2 hours, I am not sure he will really recognize you, especially if he is mounted by many riders!
Actually it's hard to answer to your question! It depends of many things: for how long have you been in contact with him before 2011? And how many times per week did you saw him ?