Noticed lately that my egg is slow to heat up. More specifically, when running up to high temps for steaks, it comes up slowly to 250-300, seems to stall, then runs up to 400-450, stalls again, then runs up another 100 or so to 500-550. After stalling again, it will go to 600-650, at which point I usually can't stand it anymore ans start cooking. Results are fine, just frustrated with how long it takes to run up. 30-40 minutes or more to reach searing temps. Impatient, or normal? Seems longer than usual. Any thoughts?