Well, let me show you this. This is a spun bearing and I'm pretty sure you'd know whether or not this is your problem. And I believe we've already ruled it out, but if you're curious here's mine. IMG_0325.mp4 video by BrandonL2000 - Photobucket
And yes I mean like springs rockers lifters that kinda thing. But if the sound has went away it's possible with the stuck lifter idea... possible.
Regardless, I think first step for you is to do an oil change, you don't want to keep seafoam in the crankcase long. So do a good oil change, check for any bad signs in the oil, and let us know. If the noise comes back, use a stethascope and listen to your valve covers and you might be able to pinpoint an area of noise.
Lastly, given none of us but you and a friend have heard the noise, hell it coulda just been belt/pulley noises that were ticking. Just a thought