Unfortunately GBL I was premature with that comment. A week or two later the issue was back but worse than before.
But... there is a happy ending to this story.
Last weekend I did some investigating and noticed the plastic outlet pipe connection coming off the top of the fuel filter was on the loose side. Kinda ironic considering it was a bitch to get off when I changed the filter recently. My hunch was the two O rings inside the connector were now damaged/worn from the removal process. So I cut the plastic fuel line with a craft knife removing about six inches of line and the offending connector. Then I cut a piece of 10mm I.D. rubber fuel line the same length and fitted it in place using hose clamps. This gave me a good seal around the filter outlet pipe and the cut end of the plastic fuel line. I also used Heldite on the fuel line end. I picked the O rings out of the connector and the lower one appeared to be damaged slightly. Not badly but probably enough for air to sneak past.
So far after a week and about 5 cold starts I haven't had a hint of bother. So hopefully that's the end of the saga.