Hello, Cliff,
it appears that you are describing the postcard issued right after the disaster that actually shows the Olympic, starboard side, dressed in flags. I have this postcard, too. On the left hand lower side is a hand-written scrawl acknowledging the Titanic disaster and in the right corner it says "Spithead Series"
My card was postmarked 3 May 1912, so apparently they were manufactured sometime in the third or last week of April 1912.
I purchased mine for about $30 US this year, though I have seen them go on eBay for as high as $120 US...