domain changes from custom to smugmug.com on upload

imajica

I just noticed something, and it may have always been that way, but i just happened to notice...

I have a custom domain, and it works fine. When i click on upload it goes from www.customdomain.com/..... to www.smugmug.com/...... and it goes back when i click on "view on site" after.

Only reason i bring this up is i just setup my email on my custom domain for the first time. That does work. Then i saw the switch when i click on upload or organize. Never noticed it do that before, but it may have and it never crossed my mind to notice. I just want to know if that is normal or not.