If you are unable to locate people you recently added when using the search feature, chances are this has to do with when you added those profiles. Please note that it takes a few days before newly added profiles are indexed. Therefore, until they are-you will not be able to locate those people using the search, photo tagger, event or document tagger features.
* Update: As of Wednesday, April 13th we started including information on the Search page regarding when the index was last updated. "Profiles created or updated before XXXX"