Don't worry too much Martin. Several have flown without incident since. Anyway, that flight was stating in freezing temperatures, probably went over the pole and landed in cold conditions. Shouldn't be anything like that involving Jamaica.
It's odd what ice can do. When I was a yoof with the POED, during January 1962, I was sent out with a guy who was on call, thus taking his van (an ANCIENT Morris E type) home at night. That was a cold cold winter. The van was parked outdoors overnight, and come the morning, on several days, the windscreen wipers would refuse to work. Same story every morning, take the van to the mechanics, they would eventually wander over and try the wipers. Worked every time. Then one morning I took the lid off the wiper motor (I had a screwdriver and it was by my left knee) and there was a big greasy ice lolly in there. Solid enough to stall the electric motor. A few more minutes waiting for a mechanic in the relatively warm garage, and it became watery grease. Motor now turns.
The point of this rambling (because all that I know of flying is that fares are cheap but everybody involved makes up for that while you are a captive audience) is that there is no mention of checking for lumps of ice on the outside of the various valves.