'Unique User' number is larger than 'Sessions' number

[wjwccx]

Rybbit version: pr-705

Actually, I created a new web site to do this simple test:

• 14:58, opened the index page.
• 15:02, clicked the play button on the page.

Here is the Timeline:

Then I opened the chart of the Rybbit homepage:

Now, I found the number of unique users at 15:00 is 1, and the number of sessions is 0.

I think both of them should be 1. What do you think?