lcu overflow (2)

Hello. Encoder outputs periodically 
`
[EndEncoding]	encoder: lcu overflow (2)
`

Could you please explain what's wrong?

From the source code:
```
enum
{
  /*! The decoder had to conceal some errors in the stream */
  AL_WARN_CONCEAL_DETECT = AL_DEF_WARNING(1),
  /*! Some LCU exceed the maximum allowed bits in the stream */
  AL_WARN_LCU_OVERFLOW = AL_DEF_WARNING(2)
};
```
