New bump on the nasal bridge 2 months after rhinoplasty, what is it?

In the first couple of weeks after the rhinoplasty my nose pretty much looked perfect. After 2 months, however, a small bump became visible in the middle of the nasal bridge. This bump seems to be getting more prominent. It feels quite hard, but when I push it, it flattens for about a minute or so. It does not move. Is this bone, cartilage, scar tissue or ... ? Why did it only appear after 2 months? What can be done about it? I'm seeing my surgeon in a couple of days, but could use some advice.