No it's not; I went digging for this information the other day. However, I have a few very close people in this field who are not certified either and are independent contractors and are doing very well for themselves!
You can however, go to the AHDI website after your course and there is information and an exam if you want to take that route!
I also have a couple great websites for MT jobs that are amazing (I was given this to me by a person that uses the site) Some companies do require it but not all and once you get in somewhere and start having the job experience on top of the course you will do just fine 
I'm just starting out on the course and dug deep for information!