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Google has been known to cache the IP addresses associated with domains it has spidered. Therefore, it is sometimes slow to switch over to the new IP address. However, changing a site's IP address is a common activity, so you should not have any major problems.
Disclaimer: As you may have read here, Google is doing a very different "update" right now. Therefore, you may see some strange behaviour for awhile. We're all looking forward to this update settling down, and the promised "normal" update to follow.
HTH,
Jim