Yes, on reflection I don't think it's quite straightforward — I just took a look at one OSC I have installed (in /public_html/osc/) and there's no .htaccess but I did notice OSC has an /images folder which would become merged with the root /images folder I guess.
I just had a look at another domain on my
Dedicated Server that has OSC installed in root and what's different is that in the folder /home/accountname<accountname>/.fantasticodata there is an extra file: installed_in_root.php
Do you have this file still present?