He did. The second we got the message he tried to make the Kraang Communication Orb tell us what happened to you. Of course he broke it... but he was so determined to save you. Heck he was so determined that when you were about to sacrifice yourself or us... again, he refused and kicked you trough the portal to New York. Don't worry, eh got out fine. But that's how desperate and determined he was to save you.

He still cares for you Leatherhead, even if not that deeply anymore. But nothing will ever stop him form seeing you as his closest friend. That much I can promise you.