An extra + sign added to the results of subst

[Skyblues]

From the examples I am going through, this one is for substitution:

The example says:
subst( 2*x^2 – x, x = a + 3 ) returns 2*(a + 3)^2 – a – 3

but I'm getting:
returns 2*(a + 3)^2 + – a – 3

Any idea why I am getting the "+ - a" ? I realize it means the same thing as "-a" but I don't know why the extra + is added.

Thanks,
Jim