See now I was sorta wondering that too. Sheez all these years I think I'm doin it right, and now I have to wonder.
Look, I'm not a mechanic, and I own a Massey, not a Deere. But it seems to me it comes down to one of these two options:
1. You're farting incorrectly.
2. The seat switch is faulty.
Just be careful, because failure to do the first one correctly may in fact void your warranty. So check your JD owners manual
:sidelaugh