Will new canvas & flys need waterproofing ?

Purchased a new Jayco Hawk Outback campervan last July- sat in the shed since, but off to Tassie last week in May for a month. Could strike some wet weather and a mate reckons the canvas, flys etc.will need a water proofing treatment,being new. Who would you listen to (all due respects to Slippery!!)

The salesman (seemed OK ), reckoned all the rag work did not require any further treatment, just make sure when it was packed away for a while to make sure it was thouroughly dry (commonsense). I am well aware salesmen have the gift of the gab programmed into them (sorry salesmen!) to promote and sell there product,So should I believe him?

If anyone can give me some advice on what to do it would be most appreciated.
Also can anyone tell me by experience are there any problems to be wary of with the Jayco model I have bought, it will not be doing any severe off road stuff, just an odd corrugated dirt track etc.
For hard going I just use the traytop with canopy ie. Simpson Desert and trips as such.

Hoping you campervan blokes can help me out Regards Nick