Sudden change - 3 week old very sleepy

[ParsleyCake]

I'm probably being stupid but I can't help worrying. My 3 week old has slept like a log today and althoughh he seemed very alert and normal when I finally woke him for a feed and nappy change he went stright back to bpa deep sleep after a 15min feed and now is back to sleeping like the dead. I'm a paranoid new mum so I checked his temperature and its normal, he doesn't seem too warm or cold, and he wears a breathing momitor at night which is ticking reassuringly as normal. It's been a 12 hour stretch of minimal feeding (not so minimal to be alarming though) and constant deep sleep.

Could something be wrong?

[ParsleyCake]

Never mind. He's fine. He kept me up all night starting from about an hour after I posted this.