diff --git a/source/reference/object-id.txt b/source/reference/object-id.txt
index 53294f7ac27..2b2fe6c340c 100644
--- a/source/reference/object-id.txt
+++ b/source/reference/object-id.txt
@@ -30,9 +30,19 @@ additional benefits:
   <ObjectId.getTimestamp()>` method.
 
 - sorting on an ``_id`` field that stores ``ObjectId`` values is
-  roughly equivalent to sorting by creation time, although this
-  relationship is not strict with ``ObjectId`` values generated on
-  multiple systems within a single second.
+  roughly equivalent to sorting by creation time.
+
+  .. important::
+  
+     This relationship is not strict with ``ObjectId`` values 
+     generated within a single second. This can happen if the 
+     values are generated by multiple systems (or by multiple
+     processes or threads on a single system) within a second,
+     or as a result of clock skew on the client side, which
+     would result in non-strict behavior even for entries that 
+     are multiple seconds apart. This is because the ObjectId
+     is generated by the client driver rather than the mongod
+     process upon insert.
 
 Also consider the :doc:`/core/document/` section for related
 information on MongoDB's document orientation.