S3 Exists panic error

[scohen28]

I'm using this code to test whether a file is found in an S3 bucket:

s := s3.New(auth, aws.USEast)
b = *s.Bucket(AmzBucket) // the bucket to check
ok, err = b.Exists(amzPath) // the path/prefix of the object to check for

I occasionally get this (even though the object exists):

panic: interface conversion: error is *url.Error, not *s3.Error

goroutine 1 [running]:
runtime.panic(0x359640, 0xc2102cbfc0)
/usr/local/go/src/pkg/runtime/panic.c:266 +0xb6
github.com/crowdmob/goamz/s3.(*Bucket).Exists(0xc2106ef800, 0xc2107e3f00, 0x96, 0x0, 0x0, ...)
/...myapp/github.com/crowdmob/goamz/s3/s3.go:245 +0x1e7