Can this be blight already?

So yesterday we popped to the garden center to buy a couple of things and ended up coming out laden down with some brilliant tomato plants we didn't mean to buy.

I was just potting them up in the greenhouse when I noticed the stem on one of them has gone a bit grey. Could it be blight already? It's a suttons grafted tomato and only about a foot tall. I took it out of the greenhouse as soon as I noticed the grey patch, and it's now sitting outside in a pot all on its own.

What do you think? Should I cut the grey bit of the growing shoot off to be on the safe side and let a side shoot take over?

 

It does look a bit iffy.
I'd cut it off, a young plant like that shouldn't be diseased already.