Just a note that "small" or "m1.small" build sizes are deprecated - and have been for some time.
If you have upgraded your account - then likely be default you are using the new "standard" size. "hi-speed" is also available. You can always use a label "standard" or "hi-speed" to ensure you are getting the build server you expect.
The deprecated small size will still work in the short term, but will result in much slower build launch times.