@ Boogaloo .... I owe you an apology. I didn't go back a page to see that you had already provided much of the information I had asked for AND that you had taken the correct step of having your knee looked at.
So, based on that information, I'd say it is a bit unusual to have the incision open up after this length of time, but it doesn't apperar to be anything to be concerned about just yet. Keep a watch on it and see if there are any changes in the next few days. Hopefully anything you notice will be positive and it will begin to close.