4-year-old wetting pants

Hi all,
My daughter potty trained last march (when she was 3.25), and it went
pretty well, and pretty easily. She's been night trained since May.

The last few weeks, she's been having accidents. Just wetting her
pants slightly. She has ALWAYS resisted our suggestions to go pee, and
so we learned early on to just leave her alone - power struggles were
counter productive. She figured it out mostly on her own. She *still*
hates it if we suggest she should go pee. She resists it, even if it's
been 4 or 5 hours since she last went, and she's about to burst.

When we were traveling, (not on the road, but while we were at
grandparent's house) it was the worst - she had 4 accidents in 3 days.
On the 3rd day, I took things in hand - I figured she was out of her
routine, and she didn't know where the bathrooms were as easily, she
had Xmas gifts to play with, whatever, but every few hours, I took her
pee. She didn't like it much, but grudgingly accepted it.

Anyway, we've been home for 5 days, and things are better - only one
accident.

My husband is annoyed at the situation - she's been trained for so
long, and he feels she knows better, and can control it. She DOES have
very good bladder control. She can go a LONG time without peeing. For
example, she goes pee right before bed, and sometimes waits for a
couple of hours after getting up to go pee for the first time (and
she's wet the bed exactly once since she was potty trained). When we
were traveling, I only insisted she go about every 4 hours.

But aside from traveling, she's been wetting her pants 1-3 times per
week for the last month. Why now? I've not noticed anything unusual
happening. Most of her clothes are easy enough for her to get off
herself. Sometimes her accidents happen as she's trying to get her
pants down, but sometimes they happen awhile before, and she doesn't
say anything. Her accidents are never more than a small amount - never
an emptying of her bladder.

Anyway, I've told my husband to knock off with the adult expectations,
and merely say matter-of-factly "Ok... you had an accident, so now
let's clean it up." (it consists of rinsing her pants and underpants
and putting them in the laundry), and to drop any judgemental issues.

Anyway, can anyone shed light on why this might be happening, so long
after she was so completely trained?

Cathy Weeks