As per Ratter an average of less than 10 secs a day slow is within tolerance for most mechanical movements, most manufacturers will tend to be fast rather than slow so a little unusual there. However pretty well all manufacturers will adjust to within tolerance within the guarantee period and I would suggest that being on the outer limits of the 'slow' side would entitle you to have this done. That being said,no-one should buy a mechanical watch for accuracy over a quartz, there's just no competition, said the man with one quartz and twenty six mechanicals ;-)