"He is shedding a little."
Somehow (I'm not a grammarian!), when we put "a little" after "shedding," it works as an adverb.
He is shedding.
How much is he shedding?
He is shedding a little.
If we put it before, when I hear "He is a little..." I do not expect to hear any form of verb. I expect to hear something like:
"He is a little Boston terrier," or
"He is a little sleepy today."