I took out my tstat this morning and found that the seam in the middle seemed to be splitting apart (see pictures). I noticed a weird coolant leak, which is what drew my attention to the tstat. This thing is new, within the past few months, and it is a genuine LR 180 stat.

Do I need to get a new one?

 

Toss it buy a new one not worth overheating. I keep one in the back and check fluids every time I fill up the gas well.

 

Your leak might not be coming from the thermostat. They tend to have that crack where the two halves are fussed together. I would still replace it and see if the leak is resolved, if it is keep the old one as a spare.

 

You could pressure test it say to 2-3 bar with a hydraulic pump or compressor but for circa $20 it's not worth the risk of an overheat and head damage. Change it for a new one but check to ensure that is actually what is leaking coolant.