My wife's S4 is having this exact same issue. We also believe it's due to the number of apps/processes that run after a while. She also had a few home screen alternatives that were running in the background. We uninstalled those and it seemed to fix this problem until a few days later when it re-emerged.
We
might have fixed this by limiting the number of background processes to 4 (instead of "standard" which appears to be "millions" hah). To do this you have to enable developer mode first.
How to Limit Background Processes (Must enable developer mode first) - Settings
- About Device
- Long Press "Build Number"
- The phone will prompt you to tap "Build Number" 3-4 times.
- Then click back and you'll see a new option called "Developer Options".
- Choose "Limit Background Processes" (all the way at the bottom)
- Pick "4 processes at most"
Again, we JUST did this so time will tell if this actually fixes it or not. Hope this helps.