I'm new to JetBlue and maybe there are booking tricks of which I'm unaware, but I've noticed what seem to be big Mint price increases over the past week for travel in June/July/August. There were some scattered deals on various routes I checked, but they're all gone. I haven't seen a single three-digit price for a Mint flight in days.

(Update: Checking again, two hours after posting the above, I'm seeing some fairly good Mint fares from LAX to JFK in July.)