According to the REPL the type of both (+1) and (1+) are Number->Number.
The expression ((1+) <$> (1+)) 1 checks out but ((+1) <$> (+1)) 1 does not.

EDIT: I just realized I'm an idiot because

let x = (+1)
    y = (+1)
(x <$> y) 1

works.
So this is some parsing bug, I think.
Or it's not correctly inferring the Functor instance for (+1)