Hi Peg,
You might double check that your lug nuts are tight and torqued correctly. I had creak in another vehicle that was pronounced at speeds under 5 mph but went away after that. Turned out I had 3 of the 5 lug nuts finger tight on one rear wheel... Can't blame the mechanic as it was me (whoops). So! Just to be safe I would double check them.

Although this happened on a project 4x4 for me. This experience has made me triple check all lug nuts if I have the wheels off (especially if done at a tire shop).

Good luck!
Ryan