No resources after 12/07 maintenance

I didn't log in to settlers online from 11/07 until 17/07, and I think my account froze after the maintenance on 12/07. For example, I expected that all of my copper mines would be depleted by then, but none of those copper mines (lvl 1; 720 ore) were depleted; they all had about 300 ore left. My population also didn't increase much; I thought I would have 1600 settlers today, but instead I only have 1200. My account started working again when I logged in today. This is a bug, right? I mean, I sometimes forget to switch off my gold mines just before the maintenance, and then those deposits get depleted.

I read somewhere that everything stops if you dont log in for 24 hours.