Keep in mind that the manufacturer recommend a resting period of 900ms before driving the same segment again and my code is driving them faster than that.  I'm also driving the segments with 12V instead of the recommended 16V-19V without any issues.  The datasheet says that the max coil temperature is 95C and my coils are not getting any where near that temperature so it could be fine as is.  This may be because I'm driving them with a lower voltage.