Contacting artists to tell them you purchased their work

I've recently picked up a couple of paintings from Christie's auctions from a contemporary artist that I really like. They're active on instagram, and I'm wondering if I should shoot them a note just to tell them that I ended up with the piece?

I'd love to acquire more of their work over time, visit the studio, etc. Just not sure what the etiquette is around this? Appreciate any thoughts that people have!