This is a good fare, but I don't think it is so low that it would be an 'error' fare.
I would offer the suggestion to check the timing of your BOM-DEL connecting flight on the return, that flight is historically late "a lot" and the connecting process (lol, if you want to call it that) is absurd.
I've taken the AC flights to/from Toronto/DEL before and I enjoyed the flight and the service. Generally I come back from India on European airlines simply to avoid the absurdly early arrival time into the US.