My guess is that you are just out of trim a little. Most all airplanes pull one way or another, and either a bit up or down, no matter how accurately we try to build them. That's what the trim levers on the transmitter are for. Trim the plane so that it flys correctly, and if that means a control surface is a bit "off", that's ok.

The descriptions above about needing some rudder on take off are also right on, and this is a normal and mostly unavoidable part of taking off.