You know what... i think she maybe keeping it for another reason...

He obviously has her number and he is obviously texting her for her to be texting back...

Maybe he is texting her and she wants to keep his number so the texter has an identity and she knows who it is, rather than keep asking 'Who's this?'

She just has it under a different name, so u dont go mad i reckon....

She has just got back with you... she obviously wants you...!!!