See
Rumour Control
They seem to think yes.
Also
1962-64 GSM Clasp SOUTH VIETNAM The various qualifying periods, between 24 December 1962 and 29 May 1964, were
* 30 days' service in ships operating in inland waters or off the Vietnamese coast.
* 1 day in the service of a land unit.
* 1 operational sortie.
* 30 days' service on an official visit.
Currently authorised medals
You wouldn't issue a medal clasp if it wasn't issued