I had the same with my Indian runners. I don´t know how the weather is over there. But over here the last years we have weird soft-winters, weeks where it is freezing and you can sit outside in the sun on a terrace without a jacket in the same week. We keep having al sort of cold or warm records..
And it affects the ducks. Early mating/molting/egg-laying it all is a bit off and loosy goosy. I think our mating-season is lasting already 8 months, but all so-so, resulting in really few Indian runner ducks this year.
Early mating is not weird I would say, nothing really is if you also have these weather-changes.