One problem with LEDs is that as their temperature goes up, their forward voltage drop goes down. So, as a group of LEDs gets warmer, they drop less of the voltage, so the current will go up, driving the temperature still higher, etc. With your current limited power supply, providing it works right, you can be sure that the average current to each string will be 400 mAmps, until one LED fails, then the remaining strings will get an average of 444 mAmps, until one more LED fails, then the remaining strings will get, 500 mAmps, etc. until all strings are off, with the last ones dying spectacularly.
As long as it works it will work, other than that you are driving them beyond their rated current by 33%, which, by itself, will make them have a very limited life.