Hi Spooky,
Lets put all this in perspective. No one will think you are suggesting that you served in the RCAF just because you are wearing flashes or a swatch of RCAF tartan.

In Scotland you will find tartan on everything from souveniers to biscuit tins and picnic blankets to scarves. Infact you can get a scarf in almost any tartan you like and they are not made to sell only to regiment or clan members.

I served in the British Army and if you wore something from my service to honour your grandfather I would be pleased because you are showing respect for that service too, because you wouldn't honour your grandfather with something you didn't respect.

So wear those flashes or swatch or patch behind badge or kilt pin in full view and with pride in your grandfather and the service he gave.

Peter