Nah, it'll be fine, your -1.5°F/hr ramp should hit 64°F roughly 7 hours from when you pitched. Should not cause any issues assuming the curve holds and you do hit 64°F.
fwiw, I run S04 at 65°F wort temperature. Keeps the beast that S04 can be on a tight enough leash without totally cramping its style, so to speak.
I recently did an imperial stout (1.107 OG) and didn't need my blow-off hoses...
Cheers!