oil pressure gauge noise

ok, so heres the deal. on friday i got my car ready for the track. i switched over from a plastic tube for the oil line, to a copper one. thats all i changed on my engine that day. on the way home i noticed a new ticking noise. this started on the freeway once everything warmed up. it sounds like a valve is a little too loose. so i didnt worry about it. sunday i ran it at the track all day long with no problems. just the annoying ticking on the way home. so today i rechecked the valves. the wernt too bad. so i took it for a test drive and after about 5 miles i got the noise back. i figured its because the oil is getting hot and thin. so when i got back to the house i popped the hood and put my ear next to the valve cover but i couldnt hear it. i can only hear it when im in the car. it almost sounds like when your speedo is going bad. but it does it in neutral so i know its not that. i thought maybe it was the transmission but i couldnt hear it down there either. finally i stuck my head under the dash and noticed its coming from my oil pressure gauge. i dont know if its the gauge itself or maybe just the copper tube transfering sound from the oil pump to the gauge. like i said i never noticed this sound with the plastic tube. has anyone ever experienced this? i may swap another gauge in there and see if thats it. i just thought i would check here and see what you guys think.
thanks
-aaron-