If it was "well, well" then you'd be right. Otherwise like Maroseika said...."oh, well" is a sigh of acceptance, whereas "well, well" same as "ну-ну" carries a bit ironic/sceptical feeling.One possibility:
- Он просто немного устал, по(э)тому и не пришёл.
- Хм, ну-ну...
Just FYI: Russian "хм" would be purely nasal, with mouth closed and rather strong expiration for "х". It is usually not read letter-by-letter.