I could have sworn that scratchcard stat bonuses were awarded to a random pet... but the last 6 times I've won a stat increase, it's gone to my active pet. Is this a permanent change or is it just for the 10th birthday celebration?

Permanent change. It was announced in the thread here.

Thanks! I didn't realize they posted things like this in the site updates forum. Guess I need to start checking that forum more regularly.

Yeah, they've been a lot better about keeping us updated with changes lately, and it's kind of cool. Anyhow, in case you missed it, there's a ping group too. It's in Amber's first post on that thread (I'm always afraid I'll end up pinging an entire group to the wrong places lol). :) Happy card scratching and stat boosting!