Android studio - cant find my app on device after building

I'm using android studio 1.3 , I'm running/debugging my app on my Nexus 5 - works great but after exiting the app - I cant find my app on the device.. so actually every time I want to run it I need to connect my device to the studio and run...

It happened suddenly , in the past I ran the program and it did! Stay on the device Tried on different devices.

    apply plugin: 'com.android.application'

android {
    compileSdkVersion 22
    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "app.meantneat.com.meetneat"
        minSdkVersion 17
        targetSdkVersion 22
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

repositories {
    mavenCentral()

    maven {
        url 'http://ift.tt/1CLc08h'
    }
}

dependencies {

    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'
    compile 'com.google.android.gms:play-services:7.3.0'
    compile 'com.astuetz:pagerslidingtabstrip:1.0.1'
    //compile 'com.getbase:floatingactionbutton:1.9.0'
    //compile 'com.parse.bolts:bolts-android:1.+'
    compile 'com.android.support:support-v4:22.2.0'
    compile 'com.melnykov:floatingactionbutton:1.3.0'
    compile 'de.hdodenhof:circleimageview:1.3.0'
    compile 'me.villani.lorenzo.android:android-cropimage:1.1.0'
    compile 'com.oguzdev:CircularFloatingActionMenu:1.0.2'




    //compile fileTree(dir: 'libs', include: 'Parse-*.jar')
    //compile 'com.google.android.gms:play-services:7.3.0'
}

Any help would be greatly appreciated.Thanks, Dan