Strange Observation..., Can anyone tell me whats going on? Options

[Silver94CelicaOw...]

So I'm comming home from a barbeque yesterday (beautiful weather) and no sooner did I pull in my driveway, but I heard a quiet ticking sound from my engine. So i popped the hood with the motor running and it sounded like it was comming from the alternator so I wasn't too worried.

But then I realized that the sound was a little more distinct, and that the cylinder seemed to be ticking at idle. So even though the engine was kinda hot from the highway, I felt on top of the spark plug wires and cylinders 2 and 4 felt like they were ticking really hard against the plug or something.... like a *tick tick tick* against my hand. But on cylinder 1 and 4, there was no such ticking that you could feel when you touch the spark plug wire. Pretty wierd, huh?

Any idea what this could be? Only thing i could think of is a cylinder colliding with the plugs in two of the cylinders or some ticking valves or something. From what I can tell its not my new spark plugs, because they were recently replaced with new Bosch plugs but are pregapped and all tightened the same. Could somebody check to see if their motor does this at idle?? If not, do you think theres something really wrong and worth getting checked out?