H1-B approved and on vacation out of USA

Since January 2012 I am on H4 and in USA and applied for H1-B in the month of May 2012. I came out of USA for 3 weeks for short vacation and came to know that my H1-B is approved.

My question is - Will there be any issue in H1b petition as currently i am out of USA? or to take a re-enter into USA with H4 visa?

Do my employer have to resubmit for new petition with new i-94?

Please help