Quad Santa Fe dumping too many pellets

Not all that unusual, really, for a Quad. You either got a good, healthy shot of startup pellets or the green light was still on, meaning that the stove came back on before it cooled all the way down. With the green light on, it will start feeding at normal intervals as soon as the dump stops. You say it rarely happens, so I wouldn't worry about it. You'll find a lot of comments in the Search for 'roaring' or 'freight train' or some such noisy start up.

No, I don't think so. As long as you don't have pellets backed all the way up into the chute. Even then, if they caught on fire, there's a safety snap disk on the chute that would shut it down. Don't worry about it. Mine have done the same thing for 4 years now. Many others post here about the same thing.

Actually, on mine, the snap disk #2 that the manual says is on the drop chute is on the right side of the stove below that snap disk #1 for the convection fan. It's the one with the black and orange wires running to it. Snap disk #3 is on the back of the auger tube and IT prevents a burn back into the hopper. I have no idea why they moved #2. On my Sante Fe, it IS on the drop chute! Both made the same year!

Well, with the very long pellets, you were most likely getting a bridging or blocking of pellets at the top of the chute which then suddenly let go and you got an abundance of pellets. It happens and sometimes the blockage won't let go and you have to dig up there with a long knife or rod to break them loose. No big deal. Just another PITA.

Instant heat pellets are low on the list of good pellets for sure.