MongoDB: is it safe to use document's ID "in public"?

I really like MongoDB's automatically generated ids. They are really useful.

However, is it save to use them publicly?

Let's say there is a posts collection, and the /posts page that takes id paramater (something like /posts/4d901acd8df94c1fe600009b) and displays info about it.

This way the user/hacker will know the real object id of the document. Is it okay or is it not secure?

Thanks