The stocked trout are fed commercial feed at the hatchery, which determines the "redness" of the flesh. It could be they changed the diet that the trout are on, you could call the Springfield ODFW office and ask them, they are good people that seem to enjoy answering questions from the public.
Best,
It's here:
Springfield Field Office
3150 E Main Street
Springfield, OR 97478-5800
Tel: 541-726-3515 Fax: 541-726-2505