ipod touch 5th gen battery

Hello, i have an iPod Touch 5th gen, im confused with the battery life, this day, i completed a full charge cycle (to 100%) so i was browsing 50 minutes and it dropped to 95-96%, browsing appstore for 10 mins 93-94%, rebooted the ipod 95%, playing subway surfers 3 rounds dropped to 92%, installed 4mb utility 91%, playing subway surfers again 89%, now the battery is 85% in 2,5 hours, is it normal for the iPod touch 5g? Using battery doctor for the percentage :)