This is nothing for Hertz cars. We have a thread about "what's the highest mileage..." and 60k+ mi is increasingly common. Hertz supposedly plans to buy a lot of new 2015 cars and dump the 2-3 year old ones they still have.

However,...

Hertz often gives the worst car they have and want to get rid of for one-ways. These frequently have out of state plates, since as no one wants them, they tend to get bounced around a bit. What was your replacement?

Also keep in mind that one-way out of FL right now is reverse flow. They would prefer to keep the nice, new cars for the hordes of vacationers descending from up north and paying peak-season rates.