They may just be exploring their new home separately. When I brought Jaffa and Magpie home from the rescue at 8 weeks old, they totally ignored each other for about 8 hours, even though they were confined to one room! Jaffa snuggled up to me and played with me whilst Magpie played with toys that were out on the floor. They then seemed to discover each other after several hours!
It's also possible that although they get on, they aren't that close. Jaffa and Mosi aren't close but when they were in a cattery together they apparently slept snuggled up to each other. Safety in numbers I reckon. Cooper and Peanut may have appeared closer at the rspca than they actually are in real life. But as long as they are ok with each other I wouldn't worry about it. Many cats, even littermates, grow apart as they get older. Jaffa and Magpie basically did their own thing once they were adults, just coming together now and again for a spot of grooming. Jaffa and Mosi interact a bit more but that is mainly initiated by Mosi! Although it's cute to see, I think it's actually quite rare for adult cats to be really close to each other and sleep together a lot etc.
