Hi Flyfisher... we've had 45 min naps on and off (mostly on!) since Katie was 7 weeks old.... they are really common.
Sometimes I have been able to extend A times and get a result - we always do it slowly, increasing only 5-10 mins at a time, and give it a few days to see if it works. I know for most people increasing A times DOES help, so it's definitely worth a try!
HTH
Bryony