Big Pilot Annual Calendar Day Change Timing

Hi guys!
Got myself a nice Big Pilot Annual Calendar Spitfire a couple of weeks back.
Was wondering if anyone knows if its normal that the day of the week changes
over between 2am and 3am? I find it odd that the day of the month changes over
between 11pm and 12am and nothing happens between 12am and 2am. Hope nothing
is wrong with my watch. Cheers!