Puppy's sensing pregnancy?

AF is due today. Hasn't shown up yet. 
I have to dogs. A girl and a boy.. Girls about 7 months and boy is 4 n a half. 
Sense this morning the boy has been following me around. Even lays next to my tummy.. When normally he'll lay by my feet or no where near me. Do you think he senses something? 
My SO and I had sex around ovulation so I feel like there's a chance. I'm just nervous to check.. Been trying for almost 1 year n a half. And don't want to be disappointed.. And not sure when I should check or to wait a few days to see if AF comes.. (Don't want it to not come only cause of stress)