This is happening on the android-one bot, most commonly on background:search:google but also on background:news:nytimes.

Stats on latest builds:

                config                     story                status  expected  failed  missing  matches
1   android-one common   background:news:nytimes  -1------------??----        20       1        2        1
2   android-one common  background:search:google  -1--------1---??----        20       2        2        2
57  android-one memory   background:news:nytimes  -1----?-----------??        60       1        9        1
58  android-one memory  background:search:google  33----?-33----2--3??        60      17        9       17

(numbers in status show how many times this error happened in a story run)


Example traceback:
  File "/b/c/b/Android_One_Perf__1_/src/third_party/catapult/telemetry/telemetry/internal/actions/action_runner.py", line 296, in TapElement
    selector=selector, text=text, element_function=element_function))
[...]
  File "/b/c/b/Android_One_Perf__1_/src/third_party/catapult/telemetry/telemetry/internal/backends/chrome_inspector/inspector_runtime.py", line 54, in Evaluate
    description=details.get('exception', {}).get('description'))
EvaluateException: UncaughtError:
Error: Tap position is off-screen
    at TapAction.start (<anonymous>:59:13)
    at callback (<anonymous>:9:30)
    at <anonymous>:17:16
    at <anonymous>:18:9

build: https://luci-milo.appspot.com/buildbot/chromium.perf/Android%20One%20Perf%20%281%29/5073
logdog: https://luci-logdog.appspot.com/v/?s=chrome%2Fbb%2Fchromium.perf%2FAndroid_One_Perf__1_%2F5073%2F%2B%2Frecipes%2Fsteps%2Fsystem_health.memory_mobile%2F0%2Fstdout

Not sure if the screen shot shows something useful:
https://console.developers.google.com/m/cloudstorage/b/chrome-telemetry-output/o/profiler-file-id_1-2017-03-21_15-11-4557230.png

+hector could you have a look?