10dpo - can you help with chart query please? ?

Question

Hello, hope someone can help?

I'm 10 dpo and using fertility friend to chart my temps.

Today when I input my temp the blue dot isn't connecting to the rest of the data and is surrounded by a black outline. I've not had this before -usually all are blue dots, connected by a blue line.

Have searched FF but can't find any explanation. Does anyone know what this means?

Here's my chart: http://www.fertilityfriend.com/home/20df54

Cheers in advance for your help