Water Heaters - pressure relief valve releasing water

Since last week every time someone takes a bath the T&P valve discharges a small amount of water. When this happens, the water looks a bit rusty. If I pull lever on the valve, the rusty water will drain and for a week or so there'll be no more leaks, then it starts again.
The valve is about 2 years old. I checked the water line pressure and it's at 60 PSI. I've flushed the tank about a month ago.
Has the valve gone bad, or is there another reason for it discharging water?

thanks,
GE

That is an odd problem. Operating a fixture should not make the T/P valve open. I would shut off the power supply (gas/electric) and drain the tank down below the level of the T/P valve and change it. The rusty water makes me think that it comes from the valve. Valves are around $10. Good luck.

That's what I was thinking exactly, off to the HomeDepot, thanks for the reply.

GE

Well, I replaced the valve, flushed the tank for about 30 min and two days later the leak is back. Rusty looking water as I pull on lever of the valve for the first few seconds, then clear.
Any other ideas?

thanks,
GE