The computer clock is on British Summer Time, which is 1 hour ahead of Universal Time (sometimes popularly known as Greenwich Mean Time).
Earlier today when looking at the font Learning_aalt_003.otf that I had exported earlier this morning, I thought that the timestamp was wrong but I was not 100% sure that I had set the checkbox.
So, when I exported the font Learning_aalt_004.otf a few minutes ago I was careful to check and note that I had set everything correctly.
I was surprised in that the font exported with a timestamp of Universal Time rather than British Summer Time. It produced 08:39:15. I checked this by studying the font in FontCreator 5.6 as well.
The created time is at 09:09:59 as I had clicked the Now button to reset the time.
I had earlier unchecked the “Automatically update modified timestamp when exporting font” checkbox and clicked the Now button before rechecking the “Automatically update modified timestamp when exporting font” checkbox. The time of 09:17:24 is still shown greyed out when studying the project file.
Just in case there is some peculiar linking going on in the software I mention that I had the “Generate the following naming fields automatically (recommended)” checkbox unchecked when exporting.
I check that checkbox when setting the name of the font so as to get the fields named and then I uncheck it so that I can have the date set in British style. For example the date today is expressed as 14 June 2013 in British style.
I just reproduced the font you made, and that all worked as you described. However when I unchecked the “Auto update timestamp” check box, and after that changed the exported font file name., the setting was reverted, so the time was automatically updated again.
So the bug was still there, and I’ve now located and fixed it. Expect a new maintenance release soon.