It is interesting to know why that should be! There may be a number of factors including:
1. Fat finger: people who want to click off an advert shown on a small mobile screen (or a touch screen) manage to click through by mistake
2. Tablets/smart phones have introduced new people (or more inexperienced people) to regular use of the web – and the more inexperienced you are, the more you tend to click
3. People using a new device that they are unused to tend to be more exploratory and therefore are more open to clicking
4. People using a mobile device out of home/office are more open to clicking as they are less engaged with their surroundings
None of these would be particularly healthy reasons for an increased CTR.
Of course there may be positive reasons for higher CTR when using a mobile device. Perhaps people have an increased propensity to buy products when using a mobile (it is likely that people who have mobile devices tend at the moment to be richer than average so this would probably be a factor).
Whatever the reasons, it is important to understand them rather than blindly responding to statistics.