Dates for old posts got changed mysteriously twice

Hi I have this website http://rockoftruthministry.org run using the most updated version of WordPress (3.3.2).

A few days ago I noticed that three oldest post in the past were showing up on the first page of the site – this means that these posts’ date got changed without me touching them.

I could not figure it out as I am the only one that can access as the admin and there is no other user account whatsoever for the site. So I simply changed those posts’ dates to one year older, thinking that this would not happen again.

Surprisingly enough, today (April 22, 2012) when I checked the site again two of those posts’ dates got changed again to today’s date – each has a different hour which means each post’s date was changed at a different time.

The first thing I need to root out is if someone has hacked in and did those changes? Not likely as I have installed a few plugins meant to make my WP install very secure. I also have a long and most complex login password. Also, if someone did break in, why did he/she only change the post dates fro certain old posts? What’s the point of doing that?

I am really having no idea that this means. Did anyone have this problem in the past? Do you know why it is this?

I am using the Fusion theme 3.1 by digitalnature. I have a few other sites using the same theme and they do not have this problem.

If anyone can help me figure this out, that would be greatly appreciated. Thanks in advance!

Aubrey