I have been taking Zyrtec for about a month to treat my seasonal ...

Yes, this is a common side effect (although not one I personally experienced). From what I have read elsewhere it does stop once you stop taking Zyrtec but you may experience withdrawals when you do try to stop taking it.

The website Askapatient has a lot of people sharing their experiences both being on and getting off the drug. There are also a couple of blogs written by people who have managed to get off Zyrtec: zyrtecwithdrawal (lots of advice on how to handle withdrawal and lots of feedback from people in the comments) and zyrtecsideeffects (my story in full) are both Blogspot blogs. I will include direct links at the bottom of this post but don't know if they will be allowed. Try googling 'zyrtec withdrawal' and following various links. The information and support is out there it is just a bit tricky to find. Good luck!

http://zyrtecwithdrawal.blogspot.com
http://zyrtecsideeffects.blogspot.com/
http://www.askapatient.com/viewrating.asp?drug=19835&name=ZYRTEC