1996 Chevy Cavalier Lifters

I recently bought a Cavalier with 83000 miles on it. I bought it from a little old lady (yes really!) The title was transfered to her 10 years ago when the car had 73000 miles. Her son told me that for the last two years she only drove it to the mailbox, approx. 200 yards from her parking space. Needless to say the car was sitting for much of the last 10 years. I was told the oil was changed regularly, but I have no way of knowing for sure. The oil is however, very clean. That's the history, now the issue.

It was missing the muffler strap bracket which caused the entire exhaust to sag all the way to the manifold causing a small exhaust leak. I replaced the strap and donut gasket. When I started the car it sounded great and I was happy. I didn't let the car warm up all the way at this time, the exhaust was quiet so I left it alone.

The next time I started it, (it isn't registered or on the road yet) it was running long enough to get to temperature. When it is cold it is nice and quiet, but as it warms it develops a ticking noise, slowly getting louder. It almost sounds like an exhaust leak, but I can't find one. It is definately not leaking at the donut gasket and don't believe the manifold is leaking at the head. I am sure if it was, I would hear it even when cold. I believe it is coming from the top front of the engine, but I can't tell for sure.

So I am thinking it is a lifter; although, I would think a lifter may be louder when cold than hot.

My questions are:
Does it sound like it may be a lifter?
Given the car's history of sitting for long periods, is it possible that the hydraulic lifter/s may just need a 1/8 turn or so to tighten it/them up?

The oil is clean and I have no reason to believe that it wasn't changed regularly, so if I assume that it was, is it possible that it sitting for so long damaged a lifter when I drove it home bringing it up to 60 mph for the first time in at least 2 years, maybe more?

TIA for your help. Its a very nice little car in great shape, I want to get to the bottom of this ticking before it becomes a real problem.