Session Monitor and SBC peak session counts reporting.

We have been looking at the session count lists produced by the SBC CLI , showing peak inbound/outbound sessions.   When trying to compare these numbers to what we see in Session Monitor there is a great discrepency.      Is it because the Session Count (high watermark) figure in the SBC can be computed over a much smaller interval than what gets reported to the Session Monitor?   Any insight would be welcomed.