We lost a bunch of gyros in short order near the end of the 2014 build. IIRC, the gyroscope output should be about 2.5V if it is not moving. (This is dependent on having 5V on the power input and a good 0V ground, of course.) Ours was way off of this value, very near one of the end points, which would be interpreted as spinning very fast by the libraries. If you're just off a little bit, your problem can likely be solved by providing calibration offsets.
Here's a document covering the gyroscope. In the third paragraph on the last page, it gives the nominal 2.5V value for non-rotating.