...they may be hitting you up for hangar space. The July 2017 issue of Car and Driver has an article about storing cars in hangars. Here's an excerpt:
You've run out of garage space and cars are stacked three deep in your driveway. Time to get more real estate! Know where there's lots of room, often cheap? Airports. A hangar usually comes with security, heat, and electricity, making it the perfect place for your collection. Hangars near big cities can rent for less than $400 per month. Half that at smaller airports gets you 1000 private square feet for automotive hootenanny.
...
Outside the rows of hangars at most airports, you'll see Pipers, Cessnas, and Mooneys tied to anchors in the pavement, kept outside permanently. Sun eats into their paint, and their owners are unable to keep gear or tools nearby. But a tie-down is cheaper than a hangar. If you trust a tie-down lessee, offer to split a hangar. His or her payment won't change, and you can pick up the difference. Or find a hangar tenant who'll trade floor space for help with the bill. Just keep your cars and motorcycles out of the plane's way.