There is a document (97 pages) available in the National Archives of Australia that deal with the supply of 100 octane fuel for the RAAF that covers 1940 and 1941.
Fortunately they are available online:
A705, 164/1/975 (searching for this reference number doesn't return a result, search for "Supply of Octane 100 aviation gasoline" will give you the result)
RAAF - Directorate of Supply - Supply of Octane 100 aviation gasoline
http://www.naa.gov.au/collection/using/search/
You can also simply type "100 octane" in the search field, there are only 4 documents.
Maybe there can be found a evidence that
Or there might be evidences that this was not the case, for example if there was enough supply on 100 octane fuel available there was no need to protest.
So far I didn't read through all the pages.
Interesting find page 97: