New Whirlpool Cooktop Problem...Maybe.

Question

Hello.

I just purchased a new Whirlpool Cooktop, and noticed the elements will glow and then after approx 5 seconds will turn off and then back on every 5 seconds or so. Only 3 elements act this way, the 4th small element will stay lit without turning on and off.
Is this normal for these glass cooktops or should I contact Whirlpool for service?
Thanks.
Jim Logue.