I'm getting google images traffic first and then....[is that a trend?]

It seems all my latest sites are getting mostly google images traffic at first.
(They are not images sites, but blogs with nice long text articles and few pics and sometimes videos in each post.)
And only some of the older are starting to get more and more of the standard search traffic.

Since this happens for quite few sites now, i thought it might be some kind of a trend others are noticing too?
So my question is have you had a case where your site appears in the google images first and later when it ages and establishes it's authority goes to the web search as well?


p.s.
It seems that analytics doesn't report the traffic from google images correctly. It shows just couple of hits from there in the stats but the new visual filter tool in webmaster tools clearly shows that the image traffic is dominating big time. Which is confirmed by the fact, that the pages that get the most of the traffic are the wordpress image pages. (attachment pages)

p.p.s
When exactly an imperssion from google images is counted. You know when you click google image result, it shows the small pic on focus with the website in the background and when you close the pic it loads the site behind normally.
On which step my site counts a hit?