Not unusual at all. I'm in zone 7 and some of my incarnata vines don't emerge until late June, early July. Plants I have at the end of the driveway are about the same size as the ones in your pic. The ones near the house are significantly bigger. Probably because the brick radiates heat into the soil.

You might want to pull up some of the grass and plants growing near the passion vines.

I just went out and pulled up the junk growing near them. I hadn't done it because I didn't think they were going to come up. I was certain they should have been much bigger than these by now.