That just means you put too big a motor in it! Each motor letter designation is double the total impulse of the previous one - it's a log scale. If you stick a C motor into a small, well-built, lightweight rocket, it's going to go over a thousand feet. Unless you painted it a very bright color, you're probably going to struggle... so stick to the A motors for your maiden flight!

(Also: launch from the upwind edge of the field!)