They’re Copying You
Ironically, dogs can be copycats. There are a lot of our facial expressions and behaviors that they can mimic to varying degrees of success, depending on their intelligence.
They Enjoy the Attention
Dogs are smart—some breeds arguably more so than others—and they can quickly learn that a certain action leads to plenty of pets and treats.
If you look over at your dog and they wink at you and start wagging their tail, that might just be their way of sending you a signal to tell you they love you.
They’re Being Submissive
Sometimes they don’t look away completely but wink instead, which breaks eye contact momentarily and sends the same message.
There’s Something In Their Eye
This most basic answer is sometimes what it comes down to. Just like us, our puppers and doggos can get a bit of dirt or hair caught in the soft membrane of their eye.