Rumours are still making the rounds that Steve Jobs, Apple's CEO told someone complaining about this issue not to hold it in this way... but these are completely denied by the Cupertino-based company.
However in a press release today from Apple, they have broken their silence and claimed
"We have discovered the cause of this dramatic drop in bars, and it is both
simple and surprising.""Its seems that the formula used to calculate how many signal strength bars are displayed is wrong"
Therefore the phone, rather than showing the users they are in a low signal areas, is incorrectly showing too many bars. So when users touch the phone in the lower left corner and get the resulting drop in signal...
"Their big drop in bars is because their high bars were never real in the first place."
Oh, and to solve the problem they will be releasing a fix for this problem soon, that also makes the smaller bars bigger.... so if you leave your glasses on your head whilst losing your signal, you can still see what a poor signal you are getting!