Hidden limitation or API troubles?


About two weeks before, I’ve become to got errors with using twitter search API.

I found that it seems frequency search makes such error.
So I reduced the number of using search API to every few minutes.
After changing so, error has reduced but still happens.

Of course, my way of using twitter API doesn’t violate rate limitations.

So I’ve questions.
Twitter API changed few weeks before, do you added any rate limitations at that time? or are there any problems with Twitter API?