I found the Privacy tap in 1Password 4 and it works fine for my rMBP; but I can't find the same control in the IOS version.
The option you're looking for in the iOS application is in Settings (look for the gear icon at the bottom of the screen or toward the bottom left on an iPad in landscape orientation). Then pick Security. From there you can determine whether to use a PIN, and how long the interval will be before you must reenter your master password.
However, remember that iOS will close idle applications if it needs memory for another active application. If that happens, you will have to enter the master password again when you return to it.
THANKS hawkmoth. I don't know how I missed seeing the gear icon. But it is just where you said it would be.
I'm glad to hear our friend @hawkmoth was able to help out, Mel. I'm going to close this thread for tidiness. If you need any further assistance, feel free to open a new thread or email us.