so the beginning was a bait and switch - they made it seem like 'someone' was spying on Gus (Lalo??)
but at the end we see that he (and Mike) have built this protection system in case Lalo or other Salamancas attack
-- similar reason Mike had Kim and Jimmie followed --
the couple at the beginning were plants (they may or may not be an actual couple - they seem to be. it may or may not be their house - probably is)