My DS is 12wks and he often sleeps in the morning til 9am or later. This goes against all the suggested patterns and routines that say wake him up at 7am.

I so do not want to do that for several reasons: if he's sleeping he obviously needs to and the other one is that it gives me a chance to spend some time with my DD one on one.

As olive said - if it's an issue for you, do something about it. But if it's not, don't stress!