Always happens. People say "I am just going to test taxi" and then they are in the air and don't know how it happend. I tell everyone, don't taxi unless you are prepared to fly!

Don't feel bad. It happens in full scale too. Unfortunately there, if the plane wasn't ready the pilot dies. Saw a guy do it once with his daughter in the plane and killed them both. Not fun.

As with full scale and models, don't taxi test unless you are ready to fly!