The AHA recommends a maximum target heart rate of 170 for your age. The 100% heart rate should be around 200. I would assume that your setting of "4" would be 4 mph. If that is the case, that would be a slow jogging pace. Some people can walk at 4mph, so it's not very fast and consequently one would think it would be perhaps in the middle of your target zone.
Now, I wouldn't let your head get too twisted around this there could be a number of factors for your higher than average heart rate. First, what are you measuring it with? Secondly, when you run on a treadmill, there is no breeze to cool you. You can rapidly overheat, and this will caus eyour heart to beat faster as it attempts to cool your core temperature. I run on a treadmill in my garage in all winter. The garage temperature is often 10 degrees F., but by the end of the workout I am drenched in sweat. So keep that in mind. Third, is it possible that you're just out of shape? If you've just started this training regime, it will take a while to develop that muscle in the center of your chest. If this is the case, it would be better to back it down a little so your training results in an ultimately longer distance and endurance.
....I reread your post. Again assuming that "4" is the speed in mph, that setting results in 15 minute miles. If you're running for only 10 minutes, you haven't completed even a mile at that point. My advice would be to back it off to a brisk walk so you can stretch your time on the treadmill. A reduction of 1 mph could allow you to increase your time to perhaps 30 minutes. This is much better training than the short duration "runs" that you're doing now. What you're doing now does little to improve your cardiac endurance. If this is a gym environment, remember there is no shame in walking. It just takes a little longer to reach the same distance. ....and remember that you're on the treadmill, while others are in McDonald's......
Hows your resting heart rate?