That is strange. I just repeated your findings and shore 'nuf, exactly as you said.
Another bug: In the calculator, enter a number (1-9), enter a decimal point, enter zero(s), enter a number. The first number will be displayed properly, but the zeros will not be displayed until followed by a number (1-9). Strangely, the computations work correctly.
Also, when the decimal is first entered, it is not in the correct position, but rather appears in the lower part of the window, above the M- (in the Basic calculator).
And Apple calls this a fix? Musta hired some folks from Redmond.