That is lovely.
In the past I've founds vets send sympathy cards. When poppy died I got nothing from my vet, despite her dying at the vets. To be honest I barely even got a explanation as to why other than the brief phone call that woke me at 6:30am to tell me she died. I was too upset to question it futher.
It's the small things that makes such a big difference to customers, showing they care is so important.