There are times to ask questions, and times not to. If you are lost on something, feel free. Always do so in respect of the dojo rules and courtesy though, and at times this may mean to simply attempt without excess questions. Much of what is learnt in aikido is done through feeling, not words.
Some time ago, before I had even heard of aikido, I read a Yiddish proverb which has stuck with me. I think it goes well here...
"He who is afraid to ask is ashamed of learning." -- Yiddish Proverb