nosey old neighbors

For the first time in my life, i live in a high-rise apartment building.  Not New York style high-rise, but at 13 stories, it's the tallest building in the city.  The building is full of privately owned condos, not rented apartments.  Most of the residents are about ninety-million years old, & it seems that some of the condos are vacation homes which sit empty most of the year.  We rent our studio from a guy who (we think) inherited the place from his dead parents.  

Yesterday, as requested by the 'house rules' in the elevator, i introduced myself to the building manager.  After my interview, i walk into the office, where there is a BB-gun on the counter (or at least, i hope it was only a BB-gun.)  I explained that i had just moved into number blablabla & that Mr. Whosit, our landlord had instructed me to introduce myself & order an additional key for the building.  The manager, younger than most of the tenants at a probable 65, seemed confused that there were two of us in the apartment, & further confused when he couldn't find my roommate's info card.  He said he couldn't copy the key for me until after he spoke with our landlord, which i agreed was reasonable, & politely said he could reach my using the phone number on the card i filled out.

Shortly thereafter, I set out to walk to our nearby beach.  In front of the building was a gaggle of old people talking with the manager.  I shyly waved & said hello as i passed, & set out enjoying my sunny day on the beach.

Cut to my roommate coming home, having just received an email from Mr. Whosit, informing us that someone in the building has complained that there are two of us living in this apartment.  To me, this means that either the manager doesn't like it, & he complained, or after i passed through the gathering of elders on my way to the beach, some nosey oldie learned of our situation through the manager & they complained.  

Obviously we're pretty irate about the situation.  The landlord's parents lived here together, for one thing.  What if we were a couple?  Would it be a problem then?  Or maybe that is precisely the issue: they think we're a couple, & don't like the idea of two lesbians living in their building.  That, or they hate poor people.  Maybe both.  We can't think of anything else that would be a problem.  We're polite, quite, unobtrusive, what more could you want from neighbors?  Would they rather a young couple with babies move in?  Or an[other] elderly man that watches Wheel of Fortune at top volume?  Apparently.