Alec definitely meant more that Dean wasn't going to be happy that Alec trusted Mary enough to tell her rather than what he actually was. Alec coming clean was definitely a big neon sign of how he was feeling towards Dean's mother, even if he wasn't explicitly saying it.
"I think we need another round so we can celebrate not having to always lie to people." He made eye contact with their server and made the universal sign for another round with his hand. "Then I can answer any other questions you have." And if she didn't, Alec didn't mind that either. There were a few things he still couldn't bring himself to admit just yet, but a lot about Manticore was on the table. "Or you can regale me with a cool hunting story." He grinned.