Yea. Completely normal. Can't do LTE and a call at the same time. Sprint and Verizon can't do a call and data at the same time. AT&T drops down to HSPA+ or "4G" (lol) for data during a call.
This is correct. However one thing that started happening today with me is after the call, the phone would not connect back to the LTE. I had to toggle the LTE switch on and off again to get the LTE connection back.