What does it mean if a professor does not respond to an email about research in a week

I emailed a professor a week ago about any potential undergraduate opportunities he might have in his research lab. I have not yet gotten a response. Is this normal? the end of my email went like this, was I too pushy or was I not explicit enough with my question? would it be rude to send another email asking again? thanks for any comments

I would appreciate the chance to talk with you about any possible undergraduate opportunities you are currently offering for the Spring 2016 semester or Fall 2016 semester. I understand you are very busy. We could schedule an appointment or I can drop by your office when you are available. Please let me know if there is any other information I can provide. Thank you, (my name)