Post ID suddenly jumped from 1792 to 989824909

… and up.

I haven’t looked at my DB for quite some time and just noticed now that last year, around 2010-11-14, my page IDs jumped from the last “normal” value (1792) to (from then on) values from 989824909 (first new value on the next day) and up.

Currently I’m at 989825619.

What could have caused this?
Could this have been a plugin?

I have no idea what I had running way back then.

Thanks for your help.