Yes, I thought it looked funny too, so I checked around and found that that's also what Onelook.com says.

Then I looked for excuses and rationalizations and found that Google has 92,000 ghits for "litigous" (carefully overlooking the fact that it also has 687,000 ghits for -ious) which gives it some dubious validity.

But really I have to admit that I posted it anyway so as to have the opportunity to use the comeback to your question:
"You're right. I'm wrong. So sue me!"

[/trying-to-sneak-unnoticed-out-the-door emoticon]