If the DBAs restored a single table from backup, would there be evidence anywhere in the data dictionary?
Depends on how the DBA restored it; if flashback is enabled for the database, there could be evidence that it was restored using the 

flashback table scott.mytab to before drop;


command.  Here are stats on a personal table, before dropping, then after restoring it via the above command; I imagine other recovery techniques might also fill in the same data:

SYS@dev01&gt; select CREATED, LAST_DDL_TIME, TIMESTAMP from dba_objects where object_name='MYTAB';

CREATED             LAST_DDL_TIME       TIMESTAMP
------------------- ------------------- -------------------
2018-07-09 19:18:29 2018-07-09 19:18:29 2018-07-09:19:18:29

SYS@dev01&gt; drop table "MARK.STEWART".mytab;

Table dropped.

AtlasDev:SYS@dev01&gt; flashback table "MARK.STEWART".mytab to before drop;

Flashback complete.

SYS@dev01&gt; select CREATED, LAST_DDL_TIME, TIMESTAMP from dba_objects where object_name='MYTAB';

CREATED             LAST_DDL_TIME       TIMESTAMP
------------------- ------------------- -------------------
2018-07-09 19:18:29 2018-12-15 03:09:31 2018-12-15:03:09:31

SYS@dev01&gt;


Now the DBA could have defined triggers to monitor table creation and deletion, and auditing could capture such activity if enabled.