MEMORANDUM *
We need not resolve at this time Appellant Shirley Klahn’s arguments challenging the administrative law judge’s (ALJ) rulings finding her not fully credible and rejecting her doctors’ opinions about the extent of her disability. Even if Klahn’s arguments on those issues fail, it appears she may nonetheless be entitled to benefits under our holding in Lounsburry v. Barnhart, 468 F.3d 1111 (9th Cir.2006). The ALJ has not yet addressed Lounsburry’s impact on this case, so we remand to the ALJ for further consideration of Klahn’s claim in light of Lounsburry.
The Commissioner contends that Klahn waived any argument based on Lounsbur-ry by not raising it until she submitted a Rule 28(j) letter shortly before oral argument. We may consider an argument not presented in the opening brief if “the failure to raise the issue properly did not prejudice the defense of the opposing party.” United States v. Ullah, 976 F.2d 509, 514 (9th Cir.1992). The Commissioner points to no prejudice caused by Louns-burry ’s late appearance, which is not surprising. The Commissioner was aware of Lounsburry, having cited the case in her *475own brief. If the Commissioner believes there are grounds for denying Klahn benefits even under the rule established in Lounsburry, she will have a full opportunity to raise those arguments before the ALJ on remand.
The parties shall bear their own costs on appeal.
VACATED AND REMANDED.