If you suddenly got huge traffic and 90% come from search engine. Is this against Google Adsense TOS?? for example: your daily traffic is: 1000 but suddenly u got 15000 What do you think about it?
Search Engine traffic is never a problem. Sudden change in traffic means your SERP has improved. It should cause no problem.
If suddenly people interested about something & search it on search engine many times & found my site....then what do you think about it?
Yes, if you experience a spurt of growth in SERP traffic it could be that your site niche has a boom in the offline world. Example people are warned to eat more cabbage to prolonged your life and your in the cabbage niche. If you want to make further analysis have a look at Google Trend. And for the initial question about Google having a problem in the sudden peak I think you can see the answers mentioned by others DPers which is No Problem.
Its not an issue - but sometimes google guys get supesious on in ECPM .... but when proved it is genuine - its accepted .
Even though it doesn't happen usually, Because you get ranking ups and downs in search engines with time frame, but still if it happens you're absolutely safe as far as it is really organic traffic from search engines.
If majority of your traffic are come from search engine, I think it safer than you got direct traffic.
Means more money, I never mond more traffic why would anybody. Its like a good day for me. however i always have more then that. lol...