Just come back from Singapore last night, dident have a visa but when i look at the stamp now i got 60days, new rules or just a mistake?

If you had no Visa it is a mistake. You should go along to Immigration and get it rectified.

You will be on overstay after 30 days.

It looks like you have some other stamp on your entry date stamp. Did you get a tourist visa at a Thai consulate or Embassy? If so, you get 60 days, that can be extended. If you had no visa at all, you get a 30 day permit to stay, not a visa. I know, clear as mud... Do you or did you not send your passport into a Thai Embassy or Consulate for a tourist visa? If Yes; 60 days, If no, you better go see your local immigration office before 30 days are up...