Hertz - "TB" on key tag - clarification please

I think this has been discussed previously, but after about 45 minutes of searching I come up blank. My current rental has a large "TB" written in red marking pen on the key tag. I din't notice it until I arrived at my destination. My understanding is that this means that the car should be pulled from the rental fleet for return. Is this correct?

Aside: The car in question is a 2001 Mazda Millenia with over 20K miles on it.

Thanks,

CWPFLY

TB stands for "Take Back" I think. I've often seen this on stickers on car windshields in Hertz lots. The car you got is probably due to be taken off fleet at the end of your rental.