What would be the most polite way to broach the subject of the recent exterminator visits to the condo next door to mine? "Hey, I'm not nosy, but I heard a bunch of noise in your house during the day yesterday [when the neighbor normally works] and happened to look out the window and see the Orkin truck parked in front of the garage. What's up?" Or, should I assume that, since the exterminator hasn't knocked on my door to say that there's a problem next door that may be spreading in my direction, I don't need to worry about anything?