I couldn't figure out why it doesn't automatically fire, but if you add this to manually fire it, you'll be good to go:
- (void)shinobiDataGrid:(ShinobiDataGrid *)grid didTapCellAtCoordinate:(SDataGridCoord *)coordinate isDoubleTap:(BOOL)isDoubleTap
// Find the cell that was tapped.
SDataGridCell* cell = (SDataGridCell*)[self.shinobiDataGrid visibleCellAtCoordinate:coordinate];
if ([coordinate.column.title isEqualToString:@"Title"])
PickerCell* pickerCell = (PickerCell*)cell;