Copyright rules are very strict. Twitter is from a phone. There is nothing regarding copying information off a phone. However Websleuth's has a copyright policy in place so copy and pasting to twitter is a violation. See the rules below:
http://www.websleuths.com/forums/showthread.php?65797-Copyright-Notice
All materials contained on this web site not otherwise subject to copyright of other parties are subject to the ownership rights of Websleuths.com. Websleuths.com authorizes you to make a single copy of the content herein for your own personal, non-commercial, use while visiting the site. You agree that any copy made must include Websleuths.com’s copyright notice. No other permission is granted to you to print, copy, reproduce, distribute, transmit, upload, download, store, display in public, alter, or modify the content contained on this web site.
So if you are exchanging tweets with someone you might remind them of the copyright here at Websleuths.