That problem got fixed a lot faster than I imagined!
Stuck relay contacts are 'welded' together. A spark jumps the gap just before the contacts mate, and the spark heats the metal. Enough heat and they stick. It's the nature of the beast, and while there are several ways to minimize the arcing (spark), I wouldn't think you have any other electrical problem(s) that would have caused this.
Old contacts that are dirty and pitted are more prone to getting stuck. You can clean the contacts to a flat surface if enough metal is left, but if you do this - it would be good to adjust the regulator correctly so your charging system is in optimum condition.
If it's an older regulator, I'd consider buying a new one, and clean your old one and keep for an emergency spare. I think $35 is about the going price. A new one would be already adjusted and should be problem-free for many years. And having a spare you can slap on is a good idea.
Once I had a regulator malfunction on a long trip, which caused the amp meter to go to high current pull (welded contact causing max drain from the generator). I found out the hard way that running this way for even a short time caused the generator armature to sling out solder and then die!
You asked about normal amp meter indications at idle. Assuming your battery is fully charged, you should see only a slight 'tic - tic' on the meter at idle. Perhaps slightly on the negative side if it's a low rpm idle. A faster idle give a higher 'tic' rate on the positive side of the meter.
A slightly discharged battery will show a strong 'tic', higher in the positive side until the battery is recharged - then it's back to the slow, soft 'tic'. Leave the lights on for a minute, then start, and you'll see perhaps 2 minutes of high charge.
