Behavior of Part inside Function

The following gives some strange "Part" warnings

Clear[f];
f = Function[{x}, x[[1]] == x[[2]]]

However if I execute the second line again, it works without warnings, any idea what's goin开发者_运维技巧g on?

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Are you sure? I don't see any warnings in version 7.0.1:

In[1]:= Clear[f];
        f=Function[{x},x[[1]]==x[[2]]]

Out[2]= Function[{x},x[[1]]==x[[2]]]