I have heard a few people adding "just" to the phrase "be about to" for emphasis. For example:
I am just about to answer that.
But by definition, "be about to" means that you're going to do something very soon. In that sense, isn't adding "just" kind of redundant? And if adding "just" is ok, what about "almost" or "nearly"? They don't seem to roll off the tongue as well as "just" to me, but there shouldn't be any reason they're any less correct than "just".