No, unless you've left the speakers out in the extreme cold, in a garage, say, in the winter. The cold causes the magnetic ferro-fluid in the tweeter to thicken, which would damp the tweeter diaphragm movement, producing dull-sounding highs. That's the theory, anyway. I've never tried it, but that's what Ian C told me.
Just let them come up to room temp, and they'll be fine.
(Magnetic ferro-fluid surrounds the voice coil; it helps dissipate heat from the motor assembly.)
Axiom Resident Expert