DH: Short - A continuity error? or some other explanation? (chapt 9 spoiler)

[Gary]

No: HPFGUIDX 172230

This kind of jumped out at me on my first read.

Early on, Hermione reveals that she altered her parents' memory and
sent them packing to Australia. Later, in chapter nine, (around page
190-200 or so, I don't have the book at hand here at work) they were
going to do a memory charm on the two death eaters that went after
them in the cafe, and when Ron said he'd never done a memory charm,
Hermione claimed that she had also never done a memory charm. So how
did she alter her parents' memory without a memory charm? Is this a
simple continuity error, or is there some other way of altering
memories that she might have used on her parents?

Trivial issue, of course, but I found it mildly annoying.

Other than that I thought the book was fabulous.

--gary