This morning, no drips. This afternoon at 84F, drips. OK, that's two days now that it drips only when temp increases. I've removed the cap and vented the tank twice. So I suppose it's expansion that pushes fuel out of wherever it pushes it out of.
In my case "this day and age" is 23 years ago. I had it worked on three years ago to replace leaking filler hose. Part of that work order with Cummins states "replaced fuel breather line."
So OK it's a quirk. I believe this is the second time I've parked with the tank filled to practically overflowing.
BTW, I might drip half a cup a day, so no biggie. But of course I prefer to not drip or dribble.