On sites with less than a thousand pageviews a day, CTR is likely to go up and down a lot - as one or two clicks extra will make it go up in the percentages. Any CTR is good if it's over 2% - when counted over at least 1000 pageviews. On technical sites CTR over 1% is good.
My CTR has been at about 10-40% for several months and google seems fine with it being high sometimes.