Lantus absorption sites?

Ever since I've been on Lantus, I've either taken it in my arm or my stomach, and I never really see any difference in BG readings the next day.

However, I've started administering it in my thighs this past week, with the exact same amount and time of day, but when I wake up, my numbers have been through the roof. For instance, last night I took the same amount in my right thigh, but I woke up at 185 mg/l and took 1u of Novolog to compensate, but I just cheked again before lunch, and I'm at 250 mg/l for no reason at all! It's happened 3x for me, and when I go back to arms/stomach, it's fine. I know the thigh has the slowest absorption rate of any site, but I would have figured it would be in full effect 12 hours later.

Does anyone else have this problem? It's extremely frustrating.