Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Yes, that is exactly correct. If you are in a low-signal location, and if you hold your phone so as to contact it in that manner, you will experience a loss of signal.

I could also cause my 3G to lose signal if I held it just so in a weak-signal area, but not as dramatically.

Fortunately for me, the way I naturally hold the phone in my left hand doesn't trigger the problem.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.