I was leading a short devotional session yesterday using the Bible app in split screen mode - Bible on one side and notesfile on the other

Then I noticed that the notes icon (red star just before verse 5) was disappearing and reappearing again!
It seemed to cycle every second - probably for around 10 seconds - and then it stopped.
I haven't been able to reproduce it since.
This is running 3.5.0 on an iPad 2 and iOS 7.
Anyone else seen anything similar - any ideas as to what might be happening?
Graham