[racket] Is this a bug in procedure 'primitive?' ?

When I try primitive? I get the following results:

> (primitive? +)
#t
> (primitive? (thunk +))
#f
> (primitive? cons)
#t
> (primitive? values)
#t
> (primitive? thunk)
. thunk: bad syntax in: thunk
> (primitive? let)
. let: bad syntax in: let
> (primitive? lambda)
. lambda: bad syntax in: lambda
> (primitive? +)
#t
> (primitive? cons)
#t
> (primitive? let)
 let: bad syntax in: let
> (primitive? thunk)
. thunk: bad syntax in: thunk
> (primitive? (thunk (+ 1 2)))
#f

Where I get the "bad syntax " error messages instead of #f  is this a
bug or is this the desired behavior?

Thanks,
Harry