Sounds about right, if they were pruned down to a framework this spring.
Dwarf is a relative term...

I remember having a buddleia in my first garden, it had grown rather large in front of a window so my husband cut it down almost to ground level with the intention of digging it out. Imagine our surprise when it grew back thicker and better than ever. Of course I now know that this what they love and is the best way to keep them in trim. lol