what’s acceptable to text your boss?

I'm at a pretty formal job now and have been trained up a lot by my boss. I mentioned that I was planning on getting a new cat but my housemates decided against it. Then I got home and they surprised me with a baby kitten. I was showing everyone. I showed a picture of the kitten to my boss saying "we did get the cat". I usually don't send social stuff but was very excited and showing everyone. Is this socially okay? I'm a lot younger than my boss which is why I was worried, even though I just wanted to show my kitten to everyone. I feel really guilty and anxious now because I feel like I overstepped my bounds and have been pretty upset about it.