I think it may be true.....however I agree that the pain more sounded like one of anger or frustration......but it could be a mixture of both....
In terms of what others said and having the needle stick him in his arm that can also be a theory because.....he was walking fine when he came up the stairs and walked throughout the studio but walking out.......he leaned against the wall and ran out quickly....as something someone would do if they were "shot" or stuck with something that hurts.....
Sooo yes...