It won't make the slightest difference Mo as the OP is talking about her basal insulin, The buttocks are fine for basal injections and I do it there more than I do in my legs.
I think the higher bg readings are just a coincidence Rosie and it might just be your basal insulin needs increasing, your meal-time ratio's need changing or your coming down with a cold or something and the symptoms have yet to appear. Another possibility is you have had a short Honeymoon Period and it's coming to an end.........just a few possibilities but can't say for sure!