when in doubt: don't do it.
it's always best to contact the owner of the pattern (or image... as I did for a paper for my web page development class.. it was on copyright infringement so I e-mailed the owner of the graphics i used in the paper and asked permission... she gave it.. but that short 5 seconds to send out the e-mail saved me grief w/ my instructor!).
Supposedly you have to change a pattern 10% for it to not be the same as the original...
I wouldn't do it in all honesty.
nada. taking a break.