The drag link flip will raise the axle side of the drag link, changing its angle. If that angle is different than the track bar, the drag link will be forced to move when the axle moves up or down since the track bar is sweeping through a different arc than the drag link would. This what we feel as bump steer.
It sounds to me like your drag link and track bar are at slightly different angles. When you did the drag link flip, did you move the track bar up using a track bar bracket? The picture looks like it's still a stock bracket, but I honestly can't remember what they look like. Generally, a drag link flip requires use of a track bar bracket that moves one end of the track bar (usually the axle end) to match the new angle of the drag link. If you don't have one, you'll want to get one or move the drag link back to the stock location (if possible).
Your picture looks like the drag link and track bar are close to the same angle, but it doesn't take much difference for there to be noticeable bump steer.