Travel b/w H4 to H1 change of status. Is H1 status valid?

I am currently working on H1B visa in United States. I came to USA on H4 visa and converted to H1B visa last year 2013. I have following question regarding H1B transfer .

I have a valid I797 petition which was filled in Apr 2013. It got approved .I travelled to India on 20 May 2013 during the I797 approval . I entered back in USA on4 May 2013 on H4 as my H1 was still in progress.
Although when I received my petition it was approved dated 22 Apr.

Please let me know whether my change of status to H1 is valid or not. Thanks.