I don't know I mean... This is TWICE that Bloo has appeared as elderly in this season... (I have no idea if Say It Isn't Sew has aired on television yet so I'm shoving this in spolier tags)
Spoiler Below When Bloo is dreaming about being stuck in the fabric straw for the rest of his life, he appears as an elderly friend, hobbiling a long with a walking stick or something, and I doubt that if Bloo wasn't going to grow old someday, that he would imagine himself as old... I dunno, I'm not to good a figuring out how people (or IFs in this case) work, just working out what causes certain people's nightmares....