A Reliable Measure of Inflation?

I believe I have stumbled upon a reliable indicator of inflation, as tied to consumer spending. I opened my first bank account with Bank of America when ATMs were starting to gain widespread acceptance. BofA ATMs (which BofA used to call "Versatellers") have always had a "Fast Cash" option that allowed the user to skip screens that required the user to key in the amount of the withdrawal and manually select the account number from which the withdrawal would be made. In the old days, the fast cash button would automatically dispense $40. Over time, pressing the Fast Cash button led to an intermediate screen that would allow the user to select from several preset dollar amounts, ranging from $20-$100 or so. However, these selections on the screen always lined up with the soft keys to the side of the screen in such a way that $40 was the selection associated with the button that the user had just pressed to get to that screen. In other words, by the placement of the selections on the screen, the software enforced an assumption that the most likely selection would be $40.

Recently, I have noticed that the software now associates that same button with a withdrawal of $60. I do not think this is an accident. I suspect that someone in the bank discovered that most users now opt for a $60 withdrawal, which caused the bank to change the software so that a withdrawal in that amount would be the most obvious selection for the user. I assume that the increase in the "default" withdrawal amount is a reflection of the fact that $40 does not go as far now as it did 25 years ago.