350 TBI Timing Chain Question

[DRS 95 Silverado]

Had common would it be to have a stretched timing chain on a very well maintained 350 TBI in my 95 silverado with about 67000 miles on it but a lot of it short trips. It had been running poorly for quite a while. Last fall I went thru the electrical system, wires, cap, module, plugs etc. That helped a little. Yesterday I decided to look some more and put my timing light on it. It was retarded quite a bit. Put it back to zero, reconnected timing wire, reset computer and it runs like a top now. I did have the intake redone years ago and yesterday when I went to move the distributor it didn't take much to loosen clamp and turn it like maybe the mechanic had not tightened right. I got it locked down good now. I'm wondering if it moved over time or my chain is stretched a little. Quess i'll have to pull the cap sometime and rock the crankshaft back and forth to check it. Is that the best way to check the chain?  

[Colossus]

Anything is possible..