It sounds like a search engine spidering or word of mouth. Search engines have software tools called 'robots' which 'spider' - or index - the Web every so often. The basic idea is they start off with a set of pages, and keep following links to find more pages, further and further.
Depending on how your friend's website's hit counter works, these 35 hits could have been made by a single hit to each page on his site.
If he wants additional statistics in the future he can write some scripts, or there are free ones available, to log extra details such as the 'User-Agent' which for a person browsing would be their Web browser, e.g. 'Internet Explorer' or similar. Search engine spiders will have their own, e.g. 'Googlebot' I think is Google's spider name.
That's a lot of potentially uninteresting useless information...if it is so, apologies. Time for bed
