Thanks for the EASA notice...however, the generic advice about fluid rehydration would apply to all aircraft types and not unique to the 737.
(ii) Re-hydrated fluid residues.
Repetitive application of thickened de-icing / anti-icing fluids may lead to the
subsequent formation / build up of a dried residue in aerodynamically quiet areas,
such as cavities and gaps. This residue may re-hydrate if exposed to high
humidity conditions, precipitation, washing, etc., and increase to many times its
original size / volume. This residue will freeze if exposed to conditions at or below
0° C. This may cause moving parts such as elevators, ailerons, and flap actuating
mechanisms to stiffen or jam in flight.
Other Boeing types (767,777,787) do not have this advice to cycle the flaps, and as far as I know, Airbus (319/320/321) do not require this step.