Such behavior has been first observed on the SDHC, Class 4, 4GB cards by SanDisk - some of them require hundreds of ms (not units of ms as it might be derived from the SD specification) between the moment it is powered up and the moment it is ready to communicate.
We bumped into it while trying to shorten the power-on reset active timeout for the processor from 200ms to 33ms (details in the attachment).
Later observed on other cards as well.
Please, take it into account in your designs.
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