Stat2Var bug sketch plot

[akmon]

Hello. Sketch plot is a very interesting function for best fit given some points. I wanted to know how accurate is my finger calculating R^2 stats after sketching. I made a very simple example given these points:
0,0
1,1
2,2
3,3
4,4

After drawing the points I sketch with my finger a sort of line, for example: Y=0,6*X+1
When I go to stats sheet, the first colum represents the linear fit (it´s done automaticaly by HP Y=X), and the second column is the equation I obtained by sketching the line with my finger. It gets unexpected values.



Moreover the more I press STAT softmenu, the more the values changes:



Have I discovered a bug?