Yeah I noticed that too this afternoon. It's a bug that appeard after new vet modifiers were introduced. Basically, every Airborne squad with Vet 2 earned before update yet still below the current requirements for vet 2 (which is 67 XP) will be given option to Vet-up once 66 XP is reached - though because the squad itself is already vetted up to level 2, it will be upped to Vet 3. Strange, but hey - Michael likey! Got one more squad with 59 XP
Devs should look at this - but I want my 4 SPs back if it's changed! ^^
BTW.: Vetted Airborne Medic Team looks gorgeous