Strange SQLAlchemy behaviour when updating records

I programmed a small blog system in Python, Flask and made a little template where i can edit posts with CKEdit. I have five posts:

A, B, C, D, E

If i want to update post A, once i made the edit, i actually get edited +3 posts, in this case, post D. All the original content of post D is overwritten by the edited content of A and the original content of A is untouched.

This happens in all posts except the last one. If i want to edit D, i get editted the post B, but i I edit E, the post is succesfully edited.

I think it's some issue with the database pointer, but dont know how to work on it.

The update code is this:

def set_post(title, text, timestamp, page):
    if page != '': #Update
        data = Post.query.get(page)
        data.title = title
        data.text = text
        db.session.commit()
[..]

I already checked the received "page" variable is correct (flash(page) just after the if sentence).

The underlying database engine is SQLLite 3.