My 2010 Honda accord had a leaky radiator, replaced it, and one month later it is leaking again, can it just be a defective radiator or can another issue with the car be causing it to fail?

How did the radiator fail?

What brand radiator did you use for the replacement? Spectra brands come with a lifetime warranty. Also check that it's the radiator leaking and not a fitting for hose (just have to ask, no offense). Go through the entire cooling system and make sure the water pump and thermostat are also working.

The radiator just started leaking, so I had to replace it. water pump and thermostat are working, no overheating, no hoses leaking.

don`t know the brand, but aftermarket one.

You wouldn't be the first person to buy a new part and have it be defective. Having said that, you still have not addressed the earlier question about being sure the radiator is leaking. Can you be MORE Specific as to Where it is leaking? Such as around the cap or at a hose clamp, or seeming to be seeping through the metal tubing nsomeplace, or near the tank ends? Have you completely checked ALL fittings, hoses, tubes etc. to eliminate other sources of the leak that may allow it to appear to be the radiator that is leaking even though it may not be? This is all important in order for anyone to help you. Also, what is the mileage on the car? How long does the engine run before the leak starts or is it always leaking, or does it happen at a certain operating temperature? It could be a blown head gasket or bad fan causing the system to boil over in a very short time and the pressure is forced out thru joints and gives the appearance that the radiator leaks. Did you buy & install it yourself or have it done at a shop?

I know that Honda radiators have a seam along the top that get a lot of complaints for leaking.

Can't go wrong w a Spectra brand!

I have checked all fittings, no other leaks anywhere, the car never overheats, it has 60k on it, after driving for a few hundred miles I notice the reservoir gets near empty.... I have now found that the upper radiator hose is very warm as it should be, but the lower one remains almost cold? is that normal?

also the radiator was installed at a shop, and all was fine for about 2 months

It sounds like you have a failed thermostat, or waterd pump, because the cooler hose tells you that there is either a blockage in the system or that the water is not circulating thru the system. Barring those two items, it would more than likely be a blown head gasket or a cracked passagewy in one of the heads. Easiest way to check is pull the thermostat out and run it for a few days to see if the condition reappears. If the problem is the thermostat then both hoses should be about the same temperature all the time. That may of course set of the check engine light because of the temperature being off because it would take the system longer to come up to operating temp and it could make the sensors think something is wrong. If that doesn't correct the propblem you need to verify that the water pump is actually functioning. It could be spinning but the impeller that makes the water flow could be just sitting still while the shaft is turning, or the fins could have actually rotted to the point that they do not make the water flow. If all that is good you need to check for bad head gasket or craked water passage in the head(s). The shop that did the change should be able to check for all these things.