My son recently confided in me about some of his behaviors.
Believe me, that's something that I would not want to know about my DD.
When my dd#1 was about 4 years old I discovered little finger prints in the stick of butter on the kitchen counter.
I don't think my kids have ever said "Don't tell Dad."
my kids know that not only do I tell DH everything, but the deli guy at stop and shop too.
My dd's are 27 & 30, and they do occasionally remind me
I handle it exactly the way you do.
I like those "we are a unit" words.
I think when you're married it's a bad precedent to set to keep things from your spouse.