The 30-year-old was caught getting steamy with 28-year-old, GG-cupped Casey in bed on Sunday night.
The twosome, who were handcuffed together when they entered the CBB house, apparently missed being shackled together.
Their show of affection came hours after Lee insisted that that nothing was going on with the model.
Lee insisted: 'There's nothing going on with me and Casey. We got strapped to each other when we first came in...'
'We got put together and obviously I'm going to talk to her and have fun with her - she's a great laugh. She's great fun - she's so much fun.'
But during a diary session, Casey insisted that Lee has been the one to initiate things with her.
'She's a great laugh. She's great fun - she's so much fun.'
When Lee told Big Brother, 'She kept on trying to spoon me, and then half way through the night she tried to fork me!', Casey replied: 'You watch the footage and look who is trying to spoon!'
Lee previously said he would not get too friendly with anyone on TV, for the sake of children Rain, 5, and Blubell also 5.
"I’d never snog anyone on live TV," the singer previously said. "My kids would be watching.
“I find that really distasteful. I couldn’t kiss anyone when I know my kids are sitting in front of the TV, going: ‘Hi, Daddy!’"
Opsy!