It's probably because the weather has been colder but I want to believe Lilo took him outside one day and had a heart-to-heart with him. Explained that as energetic and badass as she is, she was far from the youngster she once was. It would one day to be his full duty to protect the yard and love the family.
THE TORCH WILL BE PASSED.
Until then, she'll still act coy and irrational with her affection, haha, but will train and teach him to become her prodigy.
Then again it could be the weather.