I refuse to believe for a second that your attendance was considered inappropriate; the person being burried at least would have surely been happy for you to be there and think of him or her.
Also, your intentions are to be commended regardless of what the relatives thought (it's not the relative's funeral, so they are not the yardstick).
No, different culture. That are many different cultures and OP made the common mistake of not understanding until it was too late that he was intruding on a different culture. Even though OP was in the wrong I cannot fault him for the mistake, there often is no way to know if you are not very close to the family what the correct culture is.
Also, your intentions are to be commended regardless of what the relatives thought (it's not the relative's funeral, so they are not the yardstick).