CRITICAL message is issued when tablespace usage % is negative

[philippe-ebersohl]

The messages occurs regularly for the UNDO tablespace, always on the same server.
Should negative values be returned ?

CRITICAL - tbs UNDO01 usage is -0.00% | 'tbs_undo01_usage_pct'=-0.00%;80;90 'tbs_undo01_usage'=0MB;52428;58982;0;65535 'tbs_undo01_alloc'=51199MB;;;0;65535

CRITICAL - tbs UNDO01 usage is -0.02% | 'tbs_undo01_usage_pct'=-0.02%;80;90 'tbs_undo01_usage'=-9MB;52428;58982;0;65535 'tbs_undo01_alloc'=51199MB;;;0;65535

OK - no problems | 'tbs_undo01_usage_pct'=0.00%;80;90 'tbs_undo01_usage'=1MB;52428;58982;0;65535