I am planning to travel to canada (I have a valid Canada tourist Visa) on 19th Sept and back in US on 22 sept . I am currently on F1 visa with Valid Stem extention which is valid until Dec 2013. I also have a H1 approved which will start on Oct 1. My Question is: Can I go to Canada on 19th Sept and come back to US on 22 sept on my Valid F1? Will there be any problem with no h1b Stamping on my passport? My updated I-20 from university say's h1b Approved..So I am curious if Immigration Authority at border will look for h1b stamping on my passport. Since I am travelling before oct 1 and return back before oct 1, I think there should not be a problem. Please advise me.