Must be the phase of the moon! My ricoh 3110 Dn on Sawgrass inks has done the same thing this morning!
Nozzle check...spot on.
Alignment check... spot in.

Banding across the width of a4 on a solid grey.

Doesn't show when pressed (flip flops), however have never had it before.

No answer to the problem, but you are not alone!
Janners

Hmm may look into the above suggestion.