MSNBC Hardball host Chris Matthews was called out by Jeff Weaver, the campaign manager for Sen. Bernie Sanders' (I., Vt.), during an interview Monday when Matthews brought up that Sanders still had not released his tax returns.

Weaver responded that Matthews’ wife, Kathleen Matthews, did not release tax returns when she ran for the U.S. House of Representatives for Maryland's 8th congressional district. Kathleen lost the Democratic primary for that district on April 26.

"I think we should follow the example, perhaps, of yourself when your wife was running for the Congress here in Maryland recently," Weaver said.

"Oh, here we go," Matthews said.

"You guys didn't release any tax returns. So I don't really think you're one to be in a position of talking about tax returns," Weaver said.

"I don't even know if we did release tax returns, did we? I had nothing to do with the campaign. I will check. I will check. I'll be glad to check," a stunned Matthews said.

"Please do," Weaver said.

"But you know, that was certainly strange because I wasn't involved in that campaign and you know it, at all, Jeffrey, at all," Matthews said.

"This is Hardball, Chris," Weaver said impishly.