Problems? I don't anticipate any. But, be prepared to have at-least one document (bills, bank statements, etc.) for each month that you were out of the US ... to prove that you actually served the full 3 years away from the US.
PROFESSOR OF IMMIGRATION LAW for over 10 years -- This blog posting is offered for informational purposes only. It does not constitute an attorney-client relationship. Also, keep in mind that this is an INTERNET BLOG. You should not rely on anything you read here to make decisions which impact on your life. Meet with an attorney, via Skype, or in person, to obtain competent personal and professional guidance.
You should not have any problem based on the 3 year bar.
The above is intended only as general information, and does not constitute legal advice. You must speak with an attorney to discuss your individual case.