I was reimbursed for money I spent for relocation expenses totaling $7000+ by my new job; however, they made me fill out a W9. What do I do about this on my tax form?

I used my own money (which I already paid taxes on) to relocate to a new state, but to get my reimbursement for the money I spent, I had to complete a W9. Do I now have to pay taxes again on my reimbursement because the amount was $7,000+ and they asked me to complete a W9, even though I already paid taxes on the money I spent? How do I explain this to the IRS? My job won't give me a 1099 form and I was an employee not independent contractor at the time of reimbursement.