where did u get the wallet from ? if downloaded from unreliable source, it could have been infected, and also the more probable version is that your android device
was previously backdoored from some game/app etc.
Again, never rooted. The phone is rather limited in memory, so I'm not in the habit installing or trying out new apps. All the apps that I've knowingly installed come direct from the Google playstore, plus a couple of already-paid-for apps through the Amazon appstore. Other than installing the Amazon appstore's apk file, I have not installed anything on the phone that didn't come through those app stores.
The only thing that intrigues me here is this : u generated new address and it previously had activity on it, before its creation ?
that shouldnt be possible if theres not something wrong with app.
Yes, apparently that is what happened. It was "generated" within the wallet app a few minutes before sending money to it in the previously mentioned transaction.