What am I missing?

Today I discovered that something horrible had been happening around me for years, and I never noticed.  Specifically, my cat's teeth have been quietly rotting away.  The vet removed six of them (at $150 per tooth, essentially) and he's probably going to lose a few more over the next couple of years. 

I feel terrible about it, horribly guilty that he has probably been in some kind of pain for a long time now and I never knew.  Could I have done anything different?  I have no idea.  If his behavior changed because of it, it evolved over time and I never noticed anything. 

So why am I putting this here, in my professional blog?  Because I wonder how many other things I haven't noticed, that have slowly evolved out of place in my career.  What skills have slipped?  What should I have been paying attention to and didn't?  What should I notice now, before it's too late?  It's hard to ignore the things that come flying at you every day, but sometimes you need to, to pay attention to the things that aren't screaming for attention.  I suspect the quiet things are often the more important ones.