Oli and Olin have explained well the fact that your output is influenced by the offset voltage; the reason because your Opamp saturates at 8V instead of 9, is that it's an old opamp, not designed for low voltage, is not a rail-to-rail opamp.
More in detail, it means that the inner circuit has an output stage (transistor Q14, Q15, Q20 in the figure) with resistors that offer an output protection from short circuiting. Basically the current on R6 determines the voltage between base and emitter of Q15, that drains current from the base of Q14 so basically limiting the output current to avoid burning components.
But that also means that the maximum output voltage achievable is
+V - Vcesat - Vbe that is about +V - 1V
The same applies for low voltage, and that means that it's not rail-to-rail.