When reverse engineering the script for an index, Toad places a “USE master” after the "USE " of the real db. The “use master” statement should not be generated. In most installations, it would be surprising in user db objects were (attempted) to be created in master.
/****** Object: INDEX [AK1_xxx] - Script Date: 1/18/2011 3:13:26 PM ******/
create nonclustered index AK1_xxx on COMMON.dbo.yyy (col_1, col_2)