It looks like the top center clouds (just a bit to the right) got a little messy, other than that you can't tell the difference. What did you use? I will usually use the Spot Healing Tool, then clone some similar textures over the top of that. Spot healing alone sometimes seems to leave a pattern, rather than a correction.
If you want to be 100% sure that you cannot tell the difference, try a B&W layer mask and adjust the sliders to make certain area's darker and lighter. As you make it dark you can start to see where you used the clone/healing brushes, it will usually show up as a brush sized line that is a little lighter.
After messing with your pic that is the only oddball spot I found so I think you can call it a win