Quite odd, flynnsheri. I would check what your soil pH levels are (soil pH kits are available at nurseries). I would also observe if they will change on their own after about a week of being open.

Some hydrangeas, like Nikko Blue, will have a very light blue bloom color at levels close to neutral. Other pink-blue ones may sometimes start greenish (immature blooms) but change color afterwards.

If I can figure out how to get pics on here I will try to post

My Penny Mac's always start out a kind of creamy color with just a bit of blue around the edges, then fill in with blue as the flower matures.