Is it normal to get a hard lump under the incision after an operation? (photo)

I had a lipoma surgery ten days ago but now there is a hard lump the size of a pea on the left side of the incision. My surgeon says that this is how the tissue heals but I don't understand. This is the first time I have had an operation. Do all people get that? Is this normal? Will it go away? Shall I do something about it?