Rattle at startup
 

2012 buick lacrosse 3.6 has an occasional 2 second Rattle when started. I'm thinking it's camshaft position actuator solenoid. I'm confused by a bulletin I found. I don't know if I just need computer update or change parts as well. Any help is appreciated.
https://cimg2.ibsrv.net/gimg/www.bui...1b5b933079.jpg