Vendors are busy people - some have day jobs, some are always working on conten - and don't always have time to browse the galleries ;).

I always try to credit a vendor when I can for the reason seachnasaigh mentioned, so that others know what I used and if they like it, can buy it/download the freebie. It's  not required as far as I know, but it is just darn nice ;).

Laurie