Yes, this is normal. Right and slightly down would probably be better. In fact, if you check it closely, this is probably what you will find.

Our engines spin the prop to the right (from inside the canopy), this makes the model try to roll toward the left (again, looking from inside the canopy). This effect is most noticable when accelerating upon the application of power. It doesn't matter what kind of engine/motor is turning the prop, whether gas/glow/electric. The right thrust is an attempt to help keep the model moving straight ahead.

Since models must be biased to fly up right and level, the engine/motor is canted downward a tad in order to counter act this bias and to keep the model from climbing with the application of power in normal level flight.

I usually build my firewalls absolutely square and then shim them for whatever right or downthrust I want. Sometimes, on really aerobatic models, I want the engine to be dead square without compensation through shims. The better you get, the less you will rely on such tricks, but these tricks can be very handy for those without a lot of flight time.

You posted an excellent question.