If you were gone for 7 months ... without your spouse .. you should hire a lawyer and expect an interview.
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.
No, the fact that you were placed in secondary inspection is not the reason for the delay. That said, I agree with my colleague. You will likely have an interview and if you submitted insufficient evidence with your 751 filing an interview is likely.
The answer provided is general in nature and should not be construed as legal advice as not all facts are know by the attorney, nor does the answering of this question create an attorney client relationship.
Your fear is reasonable. Hire an immigration attorney.
The information contained in this answer is provided for informational purposes only, and should not be construed as legal advice on any subject matter,not should it be viewed as establishing an attorney client relationship of any kind.