Leaky factory plug in shower valve?

We have an American Standard R540 valve, which comes with a brass plug installed for the tub outlet. Originally I tried to unscrew the plug with an adjustable wrench but when it would not budge and as I felt I might strip the nut, I decided to see if there was a leakage when we installed it rather than try to force it, hoping the factory had properly sealed it (we do not have a tub on this valve).

However, when we first turned on the water pressure we did get a small droplet at the plug seal, indicating it was not sealed w/ pipe dope or telflon at the factory. I again tried to undo it, having turned off the screwsets for hot and cold... and this time I used a seemlingly properly-sized cresecent box wrench. Still to no avail, the nut would not budge. So I ended up trying to tighten it a bit more and I am not sure it moved at all or not. In any case, we do not seem to have any droplets coming at present. So now I am unsure as to whether or not I can trust this seal or not.

What would you do at this point? The plug nut looks like brass and so I think it would strip easily if I try to force it off. At a loss on whether to assume all is well now or not.

Thanks!

If it WAS leaking, then it is still leaking. If you could not loosen the plug, then you did NOT tighten it either. Unless they used "litharge and glycerin" to install it, in which case you have to heat it before it will come loose, (but even that will be difficult now that the valve body is full of water), it should unscrew with the use of enough force.

It's been over 4 days and I still do not see any sign of further leakage. I contacted Amer Std and they checked a unit at their location and said that this plug would not unscrew... it is factory sealed apparently. They were thinking it is soldered in place (or maybe as HJ suggested?)

So... I am thinking that the original "tear drop" I saw was perhaps from another source. It seems that surely we would see some leakage over this time if there were a problem, OR is there some other explanation?

The only other choice is to send the whole unit back. I'd rather not uninstall it and replace it unless it is definitely leaking. Any further advice?

There are probably several places it COULD leak and the water run down to the plug and drip off.