I got email last night regarding mine and spouse cases status change. i checked my status it says as below. Hope it is just FP notice.
On February 17, 2010, we mailed a notice requesting additional evidence or information in this case N400 APPLICATION FOR NATURALIZATION. Please follow the instructions on the notice to submit the requested information. This case will be in suspense until we receive the evidence or the opportunity to submit it expires. Once we receive the requested evidence or information and make a decision on the case, you will be notified by mail. If you move while this case is pending, please use our Change of Address online tool to update your case with your new address or call our customer service center at 1-800-375-5283.
A request for evidence is made when an application/petition is lacking required documentation/evidence (initial evidence) or the officer needs more documentation/evidence (additional evidence) to determine an applicant's eligibility for the benefit sought. We may send you a request for evidence at any stage of our review. The request will indicate what evidence or information is needed for us to fully evaluate your application or petition. The notice will explain where to send the evidence and will give the deadline for your response. Your application or petition will be held in suspense during that time. If you receive a request for evidence and have questions about what you need to submit, you may call our National Customer Service Center at 1-800-375-5283.