It absolutely could be an estimate. The troubling aspect, if true, is that Sig would not work on it. Maybe it's a liability thing or maybe it's a "if it's not broke, we don't fix it" thing.
I also saw a review on Gunblast where the weight was seven pounds.
http://www.gunblast.com/SIG-P238.htm. They list the trigger pull on the new Mustang at 5.75 pounds.
http://www.gunblast.com/Colt-MustangPocketLite.htm. According to Chuck Hawks' site, at least one model of the 238 had a trigger pull of eight pounds.
http://www.chuckhawks.com/sig_P238_titanium.htm.