iPhone 5 vibrated for no reason while charging.

[Tcomcp33]

I have a small problem (?) with my 1 week old iPhone 5. I have noticed yesterday that when phone was plugged to the charger
it vibrated once with no reason. Vibration was the same kind like when you switch the phone to the silent mode. The phone was on a table and when
it vibrated, it did not turn screen on or show other notifications of any received or updated data. I have also checked all possible apps for any updates but no new messages in Whatsapp, facebook or any other app.
I have seen some topics where problem was that email was on automatic update and phone vibrated upon arrival of new mail but my automatic update of email has been turned off since the day 1 and in my case this is not the problem.
Do you have any advice what else this might be?

 

[Mrbobb]

Is not a "problem."

When u plug in the charger, normally u get a BRINK! But due a combination if being in silent mode and/or the sound is being re-routed to AirPlay or Bluetooth, u get a vibration in lieu of the BRINK!

Next real problem!

 

[Tcomcp33]

Otherwise this would be an explanation, but I was not clear enough when I explained my problem.
Phone was not on silent mode or connected to any other device by bluetooth or airplay.
When I connected it to the charger, it came up with normal connection sound as you've said. I left it on the desk charging and this vibration appeared suddenly after the phone was connected for some time 30-60mins and completely untouched.
I'm currently at work and my phone has been on my desk for last 4 hours untouched and it does not make any sound or vibrations. Maybe I'll check again when I'll get back home and be able to connect it back to charger.