Most people, if not all, are experiencing this. Remember that this animation issue is not happening all the time. If you are using the phone fast like I do, and if your eyes are very observant, then you will see it at some point.
When I had this animation thing, I asked my girlfriend, if she had this same issue, too. She simply said "No, I don't see it on my iPhone." She has also an iPhone 5S like I do. First I thought "S...t ! I have defective faulty phone!"
But when we met, I started using her phone the way I use it, and there it was. I was able to replicate this issue 3 times. Ofcourse it was happening on occasion. I had spend like 10 minutes playing with her phone.
When I showed her this issue, she was like "oh this is nothing, it's not important, I would have never realized it myself." 🙂
So some people, unlike us, don't even aware that this issue is there. They don't see it. But it is there. Not all the time, but there.
I am pretty sure about 5 & 5S, beacause I use them both. But I have also heard people using 6 & 6+ as well. But I have never heard about 4Ss, 5Cs or any iPads...
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I don't want to give you more bad news but the upcoming iOS 8.3 will have the same animation issue as well. 🙁(( At least the people who are using the BETA version of 8.3 say the animation issue is still there. It hasn't been fixed yet.
I doubt that it will be fixed with the public version of 8.3 either....
🙁