Every year we see some off-types in our public varieties that have a genetic mutation we call elongated upper internode. This mutation causes the internode below the panicle to elongate, resulting in panicles that stick above the canopy. Some have confused this abnormality with weedy rice. 

It seems that the occurrence of this abnormality may be related to weather - some years we see it more often than others. In any case, the frequency with which it occurs is so low that it does not affect yield.