We've potty trained pretty successfully at home and have recently braved a few errands with DD in underwear. Each time, DD has been able to hold it for 3-4 hours. She pees before we leave home and won't pee again until we're back home. I think on a day that set a record, DD peed at home at 10am, we were out till 2pm, changed her to a dipe for a nap, she woke with a dry dipe, and she still didn't pee until 6pm that evening.

So my concern is that it can't be healthy for DD to hold it for that long, when she's been drinking liquids and I know she has to go.
DD does not like when people ask whether she needs to pee, so we're trying to stop asking when we're out. (We stopped asking long ago while home.) She used public potties a few months back, so I think all of this is just a control thing.

So I'm hoping this is just a stage and she'll eventually stop holding it. Anyone's child do this?

Edited for clarification