To be clear, I’m just talking about sticking your nose up to flowers that you are going to offer. I think I learned in a Thai context. But I’ve avoided doing it in Sri Lanka, and I’ve certainly never seen someone sniff before offering. Not to take us too far off topic, but if you drop a flower it’s bad form to pick it up and offer it. That does remind me, though, that in uni I had a teacher from India. Her mother gave her the job of getting flowers to offer to their shrine. But she wasn’t allowed to use any flowers that had fallen on the ground, and she wasn’t allowed to pick them. She had to wait for them to fall and catch them before they hit the ground. I always assumed this was simply a way that Indian parents kept their kids occupied. 
Oh, yeah. Luckily they were willing to tell you what was going on. It’s not that big of a deal.