Screen tearing issues as a consequence of faulty connectors have been extensively discussed on the forum, and it appears Pebble readily replaces watches with these issues.
The issue seems to be "connected" to a rubber-mounted screen connector, which developes a faulty connection over time, and which may be exacerbated by heat.
Over the past weeks I have experienced excessive screen tearing, multiple times a day. Ten minutes using a thin cardboard shim and a dab of silicone grease for the seal and: 24 hours - and counting- of uninterupted clear screen. Cut the shim so the small brass nub is not covered, and use a glue stick to fix the shim.
Note: this will void your warranty. However, it is a simple fix, and greasing the seal while ensuring it is correctly seated when fitting will ensure water resistance (source: I have serviced and repaired many dive watches).