In reply to nignogbob: Not really. I first noticed it when I was at home and knocked it slightly sideways (not enough to cause an injury). Climbing itself didn't hurt, but it was noticeably worse after climbing indoors.
After a while (before I went to my GP) I got some hand putty. As soon as I started using it there was a massive click from the knuckle - it's not done that before or since, but seemed to offer some relief for a while. No idea if it was a good or bad thing!
My GP very quickly diagnosed it as a bone spur, which would lead to arthritis if it wasn't already arthritic. Very encouragingly he told me to keep climbing just the same as exercise would help. I've climbed loads outside during the summer and it's been fine - I've barely noticed that anything was wrong, to the point that I thought my GP had got it wrong and it had healed.
For me I think the key is not to over-do indoors climbing. I'd recommend getting it checked out by your GP though...