I'm renovating a house, this stuff abounds.
For instance:
-Adding a bathroom in the basement, so paid a plumber to put in the lines
-While he's in there "hey, your water heater is over 10 years old, if you go buy one, I'll install it for free" +$550
-Then, well, I'm looking at tying into your existing water lines, they're all older iron, you really should switch to copper, I can do that but it's extra... +$600
So $1100 of scope creep, but in reality it was stuff that needed to be done, it just got done early and cheaper.
Also, doing some landscaping in the back. Wife wants to rip out a large bed full of small rocks. "Well, if you want to get rid of the rocks, I really need to rent a dumpster to get rid of them all. And if I'm renting a dumpster, I should get rid of that patio on the side of the house you hate too and throw it all away at the same time..." $240 for 2 full days of jackhammer rental and 16 hours of hard labor later...