OSBA delay for mono output

The OSBA at high bitrates, e.g. 256 kbps, and mono decoding reports a decoder delay of 8.25 ms. This means a total IVAS delay of 38 ms.

On the other hand, separate decoding of ISM and SBA to mono introduces a delay of 33 ms only. I am thus wondering whether the OSBA implementation and/or reporting is correct.