car got towed, forgot to change my plates, but have insurance on my car

[Luvmybbgirl&hubby<3]

what do i do and will i have to pay? last night my husband was on his way home from work and got pulled over, apparently we didnt have insurance ( which we do and we pay and are never late ) the police said they were really sorry and on file is said we do not have any and towed it. the only thing i can think of is that we didnt get the plates changed after switching insurances in march, so could the insurance not match up to the plates we have? how do we get out car back and what will we have to pay? is there any way to get out of paying for this since we actually do have insurance and it was just a mistake?