Delta error is shown on first push, can be avoided?

For the first time I create a snap, register it and push.

Messages are:

"""
$ snapcraft push foobar49_7.0_amd64.snap
Pushing foobar49_7.0_amd64.snap
Preparing to push '/home/facundo/canonical/building-snaps/foo/foobar49_7.0_amd64.snap' to the store.
Found cached source snap /home/facundo/.cache/snapcraft/projects/foobar49/snap_hashes/amd64/e7131baeb945a904b8afede776e28439de104161b5c2e0e65660cf9625e8b62eba9ead689ceab01cf8fb884fe131a65b.
Generating xdelta3 delta for foobar49_7.0_amd64.snap.
Error generating delta: delta saving is less than 10%.
Falling back to pushing full snap...
Pushing foobar49_7.0_amd64.snap [==============================================================================] 100%
Processing...|
Ready to release!
Revision 1 of 'foobar49' created.
"""

Why the "Error generating delta: delta saving is less than 10%."... it's a first push, how a delta can be built? against what? if no delta is possible, this "Error" should not be shown to the user...