Many thanks. I think that it is probably the 5 minute polling of Growatt reports which has been misleading especially in a 20 minute interval when SOC was unchanged. Spurious results are a daily occurrence with Growatt. The short charge was a boost from about 95% to fill the battery and the extra charge was probably only sufficient to satisfy the usage in the period.
I have selected Quick Schedules over last couple of days with longer intervals without problems but will make more allowance for Growatt in the future and even more confidence in WW product.