What does it mean when a warning light reading "slip" pops up on the dash?

Lately, it's taken my car a few cranks to start up, even if I've already been driving awhile, stop & restart it. The car's never done this before.Very unusual for my car to act up. I had my fuel injectors cleaned, all fluids replaced, oil & air filters changed. Does this mean the transmission is going bad? I've had small oil leaks here & there, but that's it. It's a 2003 Infiniti G35 with about 70K mi..