Rain, I have the same thing going on. The connection if loose gets hot, the hotter it gets, the looser it gets, then melts and deforms a bit of the plastic, the connectors within become weak...
I got away with manipulating the electrical connectors within the fuse panel and installing the relay with some dielectric grease. But it's not a permanent solution. I hate electrical work on cars.

That's just me. I've been dragging my feet on replacing the fuse panel for that reason. I keep meaning to really get in there and see if the wiring to the headlight relay can be pulled out the back and new connectors installed and the relay mounted somewhere outside the fuse panel so that the whole thing doesn't need to be changed.
I thought I saw fuse panels in two vans at PicknPulls but that was maybe a month ago - I considered getting one, but then I was reminded that I would actually have to then do this type of work.

They should be pretty common, although I don't know about differences between model years.
The same thing is going on with my blower motor relay for the heater, but only if I hit a big pothole. "If the heat doesn't work, you just reach down here and tap tap tap with your finger on this thing," said the folks I originally got the van from. Suspension work might be the fix for that one.