You may be on good footing in that you didn't sign a non-competition agreement but, you should consult with a local attorney on this issue.
THESE COMMENTS ARE NOT LEGAL ADVICE. They are provided for informational purposes only. Actual legal advice can only be provided after consultation by an attorney licensed in your jurisdiction. Answering this question does not create an attorney-client relationship or otherwise require further consultation.
How did the customers know what competing business you went to? That will be the first question at your deposition. Be very careful with non-compete agreements if you are still in the same town. The courts do not look favorably on these restrictive agreements, but you have to pay attention on how you contract yourself with your ex employer. More than likely you will get a phone call and maybe a threat from your ex boss for taking his/her business with you. It just depends on the company and the list. Take Care!
Stephen F Wallace
2411 Penny Road, Suite 203
High Point, NC 27265