I do some of the CV sifting for one of the large consultancies, and as we prefer to have consulting staff look at the CVs and determine whether we should invite the candidates in for interview it can sometimes take a few weeks for them to respond as they are all busy working on consulting assignments.I would definitely chase it up - it probably just means that the person who looks at CVs for your particular skill set either hasn't got round to it yet (and so a bit of gentle chasing won't hurt), or could have been off ill etc and the fact your CV was outstanding with them accidentally missed (so not forwarded to an alternative CV screener).