I've also worked on the US East coast for a US company (sometime in the previous century). At that time, I was already a CPAN author, and submitting patches for perl. When hired, I asked for a clause in my contract that marked all work I did in my spare time belonged to me. That was not a problem. They never made any claim on any non-company work I've made. In fact, when they had to let me go a few years later, my manager even told me I could make (and take with me) a tape of the content of my home directory. He only asked me to delete any copies of source code of three specific programs (out of the 200 or so we made) first, as they were considered to be the most worthwhile to the company. It was never checked I actually did. (I didn't have any source of our products in my home directory though).