Hi juniorlab,
Every helicopter (with the exception of a coaxial model, such as the Blade CX) has a tendency to drift (to the left in most cases) when it's level. This is due to the tail rotor throwing air to counteract the torque of the main motor. Eventually you won't even notice it, but all helicopters with a tail rotor lean slightly to one direction in a hover, depending on which way the rotor turns. What you're experiencing is completely normal
Cheers,
Colin