Rows that get added on demand have buttons with no css class set.
Notice how the newly added rows have buttons with no css class.
To work around this I simply check for the postback and set the style in the InitializeLayout event. Shouldn't InitializeLayout only get called when a new data schema is bound to the Control anyway?
if (IsPostBack){Grid.Columns[0].CellButtonStyle.CssClass = "btnClass";return;}