5 minute fuel consumption display

The bars that indicate 5 min fuel consumption are not independent of each other on my display. When a new bar is added to the graph, the size of the previously written bars change (usually get larger). For example, on a recent trip, the first 5 min bar displayed 50 MPG. When the second and third bars were displayed, the first bar increased to 60 and 100 MPG, respectively. The second bar also increased in size after the the third bar was written. I'm wondering whether there is a glitch in the computer. Can anyone tell me if this is the way it's supposed to work. If so, how does one interpret this information. My dealer wasn't much help.

 

Thank you for responding to my question. I didn't realize that the bars move to the left. I'm likely getting getting better gas milage during the second 5 min period as you're experiencing which led me to believe that the first bar was getting larger.