That yellow thing? If that's waht you're talking about
No, this:

[attachment=o230961]

It almost looks like the rim of a peat pot.

I'd take a look at the roots, and if it's rootbound, pot up. If not, I'd at least add more soil and set it up higher in the pot it's in.

In fact, that's what I'd do with all of them. Don't worry about stressing the plants when you transplant them. Done right, they love it. Done wrong, it's still possibly better that leaving it severely rootbound. Your soil chemistry will quickly become unmanageable.

Woops, still typing and DP has chimed in. What he said, too. ^^^ :thumbsup: