Is some ice build up normal?

Carrier heat pump, about 8-9 years old. Was just serviced a month ago, checked out fine. At the moment seems to be holding temp, but the fan outside is noticeably louder than normal, sounds like it’s spinning faster. It’s providing heat to two different floors of my house. I’m in South Carolina, currently 37 degrees outside, and there’s some ice build up around the heat pump. Can’t get any good pictures in the dark, I’m a newbie with terminology. Not exactly sure how long it’s been running in the last hour or so, but it just paused and I can hear the defrost kick in. Hoping it’ll kick back on shortly. Nonetheless, humidity outside is around 85 percent. With the cold temps and humidity, and the fact that it sounds like the defrost is working and at the moment it’s holding temp… am I just freaking out for nothing, or should there not be any ice build up at 37 degrees Fahrenheit, and I need to watch it and possibly call my tech back?

Thanks.