Duvie,
Technical point on USERRA. An employer is allowed to ask for documentation of military service after 31 days, but the documentation does not need to be your orders. Any employer can demand, ask, whatever, but we are not obligated to provide orders as proof of service. I often recommend a letter from the unit because it can be more accurate. (Multiple sets of short, but continuous sets of orders ( AT/ADT/Drills, etc combinations that end up exceeding 31 days)
In the form of a FAQ from 4312:
Is an employer entitled to proof that military duty actually performed?

Yes. USERRA provides that following periods of military service of 31 days or more, the returning employee must, upon the employer's request, provide documentation that establishes length and character of the service (Honorable or dishonorable) and the timeliness of the application for reemployment. Reemployment may not be delayed, however, if such documentation does not exist or is not readily available. In general, the following documents have been determined by the Secretary of Labor to satisfy proof of eligibility for reemployment: discharge papers, leave and earnings statements, school completion certificate, endorsed orders, or a letter from a proper military authority. While USERRA does not address documentation of shorter periods of military service, if doubt exists, an employer could contact the employee's military command with questions about a specific period of service. (Section 4312).