I dont think it will be a problem although it is a kinda long cut for a scrotum! It must have been a great surprise to you at the time!!!
It sounds like you are doing the right things, they only comment I would make is if it is 10 to 20 mm long that is almost as much as a vasectomy incision, and they stitch those. Given the way the skin of the scrotum changes and moves it may be tricky to make the edges close up and at the least you should try steristrips to close the wound and hold it together. If it is not healing properly go and get a stitch or two.