I was born w/ no soft spot in my head but the doctor said it was ok and didn't need surgery, so do i now have untreated craniosynostosis as an adult?

Maybe: If the craniosynostosis is mild and very localized, this doesn't necessarily require treatment, as the condition is usually a purely cosmetic problem. If you're happy with your head shape then nothing needs to be done.

See below: If your head is normal shaped then there is likely to be no craniosynostosis. If there is a malformation then yes this is possible, easiest way is to have your local md check your head at your next visit.

Craniosynostosis: No your doctor was right - you had a premature closure which is uncommon but can happen. So unless you have some unusual facial stigmata of craniosynostosis you would not need treatment.