Bump/ridge when turning crochet work...?

If you worked the body of the hat in the round (never turning and going the other direction, just around and around in the same direction the whole time) then the texture of the ear flap is going to be different from the texture of the body of the hat. With the ear flap worked back and forth (with a "turn" instruction), there will be a kind of ridge on each row. It's not very pronounced and most crocheters probably don't even notice anymore, but if you've only ever done crocheting from one side of the fabric, you won't be used to seeing it alternate rows from right side to wrong side and so on. You can test whether this is what you are seeing by either doing a small swatch back and forth with plain sc and see if it happens there too, or doing a few more rows on your ear flap to see if it continues. But I'm guessing that if the scallop smoothing went well and it was the first row after that (the first row that started with a turn) that that is what you are observing. If so, there really isn't a good fix other than always working from the front side which would mean redesigning the ear flap in a rather unusual way.