John was attempting to do more than just kneel, though that's what you limited it to. The verse says he was going to "worship" the angel. The angel stopped him, and rightly so. I'll repeat what the others have said, we Catholics do NOT worship Mary, nor any other saint. They are NOT deities. There is one God, in Trinity. That IS Catholic Doctrine. Period.
It doesn't matter how directly we Catholics say it, most Protestants will never let go of their strawman. I always look at it this way: If we did indeed worship Mary, we must feel that it is her due as some sort of deity or semi-deity. If we feel that way about her, then why would we go to such pains to conceal and deny our belief from Protestants? Especially if we view her as some goddess.