...when you bring your knitting to class and leave your book at home (I did this today--had to call hubby to bring it to me before class).
...when you FINALLY get into Ravelry and spend 2 days NOT knitting, but simply organizing your knitting stuff online and looking up cool patterns for your 3 skeins of Tapestry or random skein of novelty slub yarn.
...when your Ravelry queue grows to over 30 items within 24 hours of joining.
Edit: ...when your DH, who normally hates leaving the house for any reason, asks to take you out to dinner just so he can get some time with you without needles getting in the way.