Erratic GPS performance

I recently bought a Garmin Edge 1050, my first cycling computer, and have so far logged about 300km without any issues. However, today about 90km into a ride and right after the start of a climb, the GPS lost connection and started dropping in and out erratically. There was no notable tree cover, and elevation was substantially higher than surroundings (being a hill). The connection only returned after around 30 minutes when we were parked up at the top of the hill for lunch. Other than the erratic route, my speed data (no speed sensor) is also all over the place (max speed over 1000kph for this section!). Here's a screen grab of the problematic section:

Once the connection returned there were no further problems for the remaining 20km of the route.

1) Is this 'normal' behaviour, or does it indicate a problem with the unit?

2) Is there any way I can mask this section of the route on connect so I can recover my speed stats?

If relevant, I have the "Satellite systems" setting set to "Auto select" (as recommended by DC rainmaker).

Cheers!

Daniel