The only thing that I could think of is they didn't need to grow more roots because they were getting enough water? Maybe with all the rain last year? I occasionally let our hostas get a little dry to encourage them to send deeper roots. But then again, I grow hostas. Much different from roses.

Roses are HEAVY feeders - did you fertilize them? Blooming puts a lot of stress on a rose (or any plant) and roses need fed twice a year at least - spring and fall. How heavy is your soil? I have LOTS of clay in mine, but when I plant my roses I make sure that I loosen up the soil well around where the roses go in, make sure they get enough water, and mulch well for winter. In spring I feed them (dry organic feed) and scrape it very well in. Also, if it is a continual bloom rose - which most HTs are, you need to dead head them before the hips form too far. That encourages further flowering and de-stresses the plant. In fall, you dead head half or all (half if you wish to leave some for the birds) and feed again.

Hope this helps!

-Marie

I'm stretching my memory a bit too far here so you may want to repost this question on the rose forum if you want to dig deeper(no pun) but there are different kinds of rootstock used for hybrid teas and some reportedly do better in southern growing conditions and some are more vigorous for northern states. Dr. Huey is one of the common ones used for grafting but I can't remember if it was the one recommended for north or south. I like planting bareroot roses so that I can get a good look at the root system and sometimes the bargain bag roses have had their roots severely trimmed or broken in shipment. They may be able to send up a shoot but not sustain that growth plus put energy into new roots.