gas spilling-different than others
Couple of things.
1 When filling, the car may have been in such an attitude such as slightly up/ down hill, or just slightly tilted sideways, to place the filler in a "more up" position, allowing more fuel in
2 Your home parking may be OPPOSITE, IE a tilted attitude with the filler slightly down
3 If this was a station with underground tanks, the fuel is nice and cool. If this was a warm day, and you got the tank "nice and full" the fuel expanded and forced it's way out
4 Some pumps are IRRITATINGLY slow, others are ABUSIVELY over--pressure, and this can dramatically change the way the tank fills
I'm not familiar with venting on the earlier cars. My 67 uses a sealed, unvented cap. The vent for my car is a small tube welded into the filler neck way up high where the filler comes out of the side of the car. This tube goes UP a few more inches to the top of the trunk, then turns down, through the trunk floor, and ends inside the rear frame rail.
So a 67 can do this same thing, except the cap doesn't normally leak, but it CAN puke fuel out the vent if over--filled