Please help diagnose leaf yellowing

[mprasek]

This is my Early Girl, whom wintered over in a self watering container. We are in Houston Texas, and this container design (and container) has been used for 2 years without watering problems. ( The soil was renewed when the plant went semi-dormant in October.) The yellowing started 3 -4 days ago.

I have attached 2 pictures of the plant. I have a tendency to over think things, and would like others input.

I checked for bugs, spots and mites, worm poo,etc. Nothing found.

Thanks in advance,
Mike




and a closeup:



links to full size pictures:

distance:
http://dl.dropbox.com/u/69116384/20130410_094340.jpg
closeup:
http://dl.dropbox.com/u/69116384/20130410_094340.jpg

Thanks again,
Mike