Both Invincible Iron Man #596 and Defenders #9 have been delayed two weeks, according to a notice in Marvel's weekly retailer newsletter.
Both of these Brian Michael Bendis-written issues have been pushed back from January 17 to January 31. No reason was given by Marvel for the delays, but the writer has previously said is recent illness would affect some of his upcoming Marvel and DC work.
There's no word on if any further issues will be delayed as a result.
Bendis' Defenders run is scheduled to end with #10, while his final Invincible Iron Man issue is #600.