Sometimes Lambda-backed APIs return 502 when using warmup plugin

Good morning everyone,

i am experiencing some 502 errors from API invocations since installed the serverless warmup plugin. What it could be? My default warmer is:

warmup:
default:
enabled: true
name: zipplay-api-warmer-${self:provider.stage}
role: ZipPlayWarmerFunctionRole
cleanFolder: true
prewarm: false
folderName: ‘.warmup’
concurrency: 2
timeout: 120
logRetentionInDays: 1
verbose: false