National for August?

[K9pal]

I have a mid size reserved for August already, but just ran across a code that gives a great rate. It's ID 5760339, apparently associated with Carlson Travel. Has anyone used this recently? Is there a problem with using it? I can get my mid size for 4 days for $119.62, all fees included, when I combine this with a free day coupon from Sams. But I don't want to be hassled at the counter. Thanks!