workout HR target

Today I looked closely to my HR graphic.  I saw a gray area that's supposed to be my target HR.  But my workout was set to 130 BPM and the line is at 80 BPM.  I looked at my runs with a limit set on 140 BPM and there the line was at 85 BPM.  I also looked at my interval training wich has 3 limits: 130, 160 and 170. On the graphic this translates to: 80, 95 and 100.  Anyone an idea where this difference comes from?