I've had SSSS in a period of higher than my usual frequency, so other than random, it may be triggered by changes in travel behaviour. I've only had it ex-YYZ, my home base, never returning home. But other than being unable to OLCI and print BP, it was really no biggie. I do the patdown rather than the body scanner for various reasons of my own, but I have found them professional about it all, if not always as interested as I am in getting the show on the road.