It's an interesting question. Omega has something called a Vintage Diagnostic Handbook - they go into detail about different things with vintage watches from a service standpoint. They also address what hands can go with what dials when replacement of hands is necessary:
Dial lumed + hands lumed - OK
Dial not lumed and hands not lumed - OK
Dial lumed by no hand lumed - Not OK
Dial without lume but hands lumed - OK
So based on this, I would say that it's very possible that Omega made watches that didn't have lume on the dial, but the hands were lumed.