If you accidentally listed your marital status as single, there's a good chance CRA will catch it during processing. When your Notice of Assessment arrives, look for details of the change. If CRA doesn't catch the error on their end, you can file an adjustment to make the correction.
*If you correctly listed your status as married but just filed a separate return (not prepared the same time as your husband's), that's completely fine. Many taxpayers choose to prepare their returns separately.