Is ignorance/unawareness Dukkha? It is usually said that the root delusions of attachment, anger and unawareness/ignorance are the causes of Dukkha. Of the three, unawareness/ignorance is the root cause. 

I see very how unawareness/ignorance can lead to Dukkha. But is there any evidence in the scriptures that unawareness/ignorance itself is Dukkha?
Dukkha has many meanings.  It also means changing, impermanent, subject to destruction, then yes, ignorance is dukkha because it is impermanent.   To put it in perspective, wisdom or Panna is also Dukkha because it is subject to decay and ending.  Wisdom ends when name-form ends.  Ignorance (as well as wisdom) is Pratītyasamutpāna-dhamma (conditoned dhamma).  The things that beings are ignorance of is the four noble truths.  that's why beings are constantly searching for sensual pleasures  (or in finer cases, pleasures from rupa and arupa bliss).  We dont know that things we are searching for are reasons why we suffer.