Why can't I do a method call after a @Grab declaration in a Groovy script?

I'm trying to build a DSL and using a Global AST Transform to do it. The script is compiling with groovyc fine, but I'd like to be able to be able to have a user use Grab/Grape to pull the JAR and just have it execute right away as a groovy script.

I then found that I couldn't do it correctly because there's a parsing error in the script if there isn't a method declaration or import statement after the @Grab call.

Here's an example:

@Grab(group='mysql', module='mysql-connector-java', version='5.1.6')

println "Hello World!"

It looks like it should work, but it complains (here's the output the GroovyConsole Script):

startup failed:
Script1.groovy: 4: unexpected token: println @ line 4, column 1.
   println "hello"
   ^

1 error

Trying different things makes it work, like an import statement:

@Grab(group='mysql', module='mysql-connector-java', version='5.1.6')
import groovy.lang.Object
println "Hello World!" ​

Or a method declation:

@Grab(group='mysql', module='mysql-connector-java', version='5.1.6')
def hello() {}
println "Hello World!"

Is this a bug in the parser? ​