Did I collapse a lifter?
 

After several runs today, I heard a loud tapping from the passenger side and am now taking the valve covers off to see what the hell happened.

The motor has been running very strong after a top-end rebuild last week.

If I can move the pushrod up and down with a few thousandths, should I just tighten the adjusting nut 1/8th turn and see if it was just loose?

Maybe you did not have the rocker locked down properly and it loosened up? If it definitely sounds like a rocker arm, then I would readjust them all to be safe.
If you keep getting ticking after valve adjustments you might have a wasted guide. That will usually, but not all the time show oil on the plug.

Number 1...
 

You were absolutely correct.
Number one intake rocker arm was almost totally off.
I couldn't believe it. I checked all of them on the passenger side and the luck nuts were tight.
Hmm.
I checked the valves three complete times before re-installing the intake manifold.
I am wondering now since I only tightened the rocker nut 1/8-1/4 turn and then tightened the lock nut that they might back off.
Damn.

Here s what I do - take the rocker down to the push rod and go an 1/8 turn, set the lock and take the nut down another 1/8 turn - sets up the lock real nice and tight.

mild valve train noise...
 

After readjusting the number one intake valve, I still hear a "little" tapping. Only at certain times though, so I am just going to go with it and see if it stays the same.
I can only hear it in the car, not even outside with the hood up.
strange...

Re: mild valve train noise...
 

The bad part is your going to hear now no matter what! Even if it aint there! It's called paranoia! It's sucks don't it!;)
Just drive it and turn the radio up.:(

paranoia...
 

When I start hearing tapping rocker arms in my dreams, then it may be time to talk to a professional....:D

Re: paranoia...
 

I know this good counselor,... he help me with this weird rear-end noises that I hear in my dreams.:D :D ;)