You really need to look at its environment in order to determine this. If you are providing the proper lighting (T5 or MH), proper water conditions (0 AM, 0 NI, 0 NA), normal salinity (i usually have it at 34 ppt), and nothing is bothering the anemone then i would say it is just normal behavior. Splitting is normal if it is done less than once a year to two and done when the anemone is relatively large.
If you fit all of these 'parameters', then I'd bet your okay and just leave it be. If not then you need to adjust.