Hi, first time on your forums. I recently bought a nexus 5 (very pleased) but when sliding it into its new case, I noticed the phone makes a sound when the case magnet is in contact with the back end of the phone. The sound is always the same, a short sound, two notes going up then two going down. Is this some kind of warning? Am I damaging my phone or is this some kind of not so helpful feature that can hopefully be disabled? Thanks for your help.