According to this tweet from Urban, Belt told him that he will be heading back to the Grizzlies now that Ross is off the DL.
I was one of the prognosticators that predicted Belt would be sent back to Fresno sometime this season, But even I didn't think it would come this quickly. I thought that he'd at least make it through the end of April. I think this is a good thing for Belt and the Giants in the long run. Hopefully, he'll be able to spend a lot of time in RF and LF in a low-pressure environment and regain his confidence at the plate. Also, if he's there for more than a month then it should stave off his 1st year of FA by 1 season.