Boyfriend checks out ex wifes facebook page?

[Yes.]

i went to the history of internet websites his visited and he visits he's ex wifes facebook page.

they have two younger kids (4&5) together. they see each other about twice a week. they were together for 10 years, married for 3 and she left him. he and i have been dating for a year and a half and ive never trusted her.
last year i caught her using the word "babe" in one of her txt msgs to him.

i was going to ask him why he visits her page, when he can't see any info but her profile pic but i went back to history and he deleted the history of seeing her page!!!! thats when i knew he was hiding something! or doesn't want me knowing...

how do i bring it up with him???

thanks.
... just imagine you doing the same thing... why would you look up your ex's regularly?
he cant see anything but her profile picture. everything else is blocked by her.