Why is my iPad 2's email not updating?

Question

The other day I was on my iPad checking my email and nothing came in, even after I manually refreshed it multiple times,I took out my iPhone and its email was updating and had multi emails that should have come in on the iPad a long time ago, then I also checked my iPod touch, emails were updated and the same emails on the iPhone were also updated on the iPod touch.
I did not know why the iPad was not downloading/updating so I tried closing email, ending it in multitasking and re-launching it but still it did not update.
I tried disconnecting wi-fi and re-connecting but still noting happened.
then I tried turned off the iPad and then turned it back on and finally the emails came in.
On another day on a different wi-fi network the same thing happened, but rebooting did fix it.
This happened a total of 4 times on different wi-fi networks.
Why is it doing this?
I am worried something is wrong with the iPad and I need to find out so I can bring the iPad to Apple for repair/exchange.
If someone has had this problem, what did you do?

Answer 1

In my email account only one device can be signed in at a time. If I run Mail and it is still Clive I cannot use safari to check my mail through webmail. The cure is to stop Mail from running when I need to access the account from another app or device. To stop Mail I double click the home button to bring up the line of recently used apps. The tap Mail and hold until it wiggles. Tap the minus sign. Then tap the Home button.
Mail will stop on its own if you move onto using another app but it takes several minutes before it actually quits.
Maybe your system has the same symptom.